Magnacut vs 20cv - Spyderco Manix 2 Lightweight Maxamet Gray FRCP C101PGY2.

 
Polymer scale deka comes with magnacut. . Magnacut vs 20cv

MagnaCut has the lowest chromium of any of the below steels but all of its chromium is in solution (no chromium carbide) and the fact that it has no chromium carbide also gives it the maximum level of corrosion resistance for a given amount of chromium. It&x27;s a true leap forward in cutlery steel, after years of pressing steels designed for other uses into knives. CPM S35VN, RWL34, Nitro-V Stainless Steel, Sandvik 14C28N Stainless Steel, CPM S30V, Bohler M390 Stainless, Bohler N690 Stainless, CPM 20CV, CPM S110V . knife edcgear knives edc edclife knifelife Magnacut 20cv Hogue HogueDeka AboutPressCopyrightContact. Model SP-C101PGY2. Mako PG series- Bohler N360 (LC200N) -allow 5 months for delivery. 2021-12-26 2042 375 108 knifesteelnerds. Post author Post published 09062022; Post category forte payment systems complaints; Post comments show multiple time zones in outlook web. carbon steel debate often ends up going in circles, one area where non-stainless steels have remained king are in the powder metallurgy, high alloy. Specifications Blade Length 7. According to their distributors, it&x27;s an equivalent of Crucible CPM 3V steel, although Carbon content in Z-Wear is considerably higher, 1. Home > Uncategorized > cpm 4v vs m4. I have been going for speed and volume and not really pulling the punches. MagnaCut is even somewhat finer than CPM-4V and Vanadis 4 Extra, the non-stainless steels that MagnaCut was modeled after. Let me start with a general statement after using this knife from July till September 2021. from 219. CTS-BD1N stainless steel toughness and edge retention are not. level 2. CPM Cruwear Steel. CTS-BD1N stainless steel toughness and edge retention are not. Crucible Industries LLC. Also, what turkeypants said. Mako PG series- CPM 20CV allow 3 weeks for delivery. elmax steel vs. cpm 4v vs m4. 20cv vs m4. LC200N also known as Z-Finit is nitrogen-based steel made by ZAPP. By Larry Connelley 2019. CPM-M4 2. from 219. IMHO, it&x27;s too early to say anything practical about Magnacut, except that it&x27;s already over-hyped. Whatever comes first. Add to Cart. Magnacut makes it seem like a dream come true, stainless, as tough as 4V if not 3V, great wear resistance etc. MSRP 149. May 03, 2022 CPM-MagnaCut. ShannonSteelLabs said Looks like i will be joining this soon. New New New. Mako PG series- CPM 20CV allow 3 weeks for delivery. 25" CTS-XHP Wharncliffe - F3 Medium WHFL The Curtiss Knives F3 Series was born out. It sounds like it will be a contender, and what little has been offered to makers has been spoken for. my boy gba. In Stock. unforgettable love episode 17 sub indo Curtiss F3 Medium Slim MagnaCut Folding Knife 3. The toughness of MagnaCut steel is better than most other steels, including the likes of CPM S45VN, Vanax, and VG10. Aug 15, 2021 MagnaCut vs 20cv(from another company) OK, so once we get past, different geometry, different ergos, different company, we can get to different steel. Vanax gives up some toughness and hardness vs MagnaCut for saltwater levels of corrosion resistance. Post author Post published 09062022; Post category forte payment systems. 154CM is high-end steel developed by Crucible Industries. south higgins lake state park reviews. c async vs coroutine. Mako PG series- CPM 20CV allow 3 weeks for delivery. 4V (and Magnacut - at least on paper) vs. 95 on the table. MagnaCut CPM-154 M390 Elmax S30V Vanax CPM-4V; What is CTS 204p steel. In this section, were going to compare our steel with other steels, and for this, I use four criteria; Edge Retention, Corrosion resistance, Ease of Sharpness, and Toughness, and I use a scale or note from 1 to 10. MagnaCut vs LC200N. 3V are two different worlds when it comes to toughness. Mako PG series- CPM Magnacut allow 7 months for delivery. I cant disagree. Mako PG series- CPM Cru-wear allow 3. So far Magnacut is living up to its design goal of a stainless 4V. CPM M4 VS Steel. More carbide and harder carbides lead to the best edge retention. These amazing knives are built utilizing years of experience in the outdoors making all of their knives built to work. 20cv vs magnacut. MagnaCut was introduced in 2021 and the brainchild of knife steel guru Larrin Thomas who designed the steel specifically for knives. HO24369 Deka ABLE Lock Folding Knife , Black Polymer Hogue Knives. Why are the Magnacut Dekas cheaper than the 20CV They&39;re cheaper by like 30 4 8 8 comments Best Add a Comment knifeflip 7 mo. Model SP-C81GPCMOBK2. 20cv vs magnacut. The main difference between MagnaCut steel and 20CV steel is that MagnaCut steel offers twice the performance of 20CV steel in toughness. Now comes with a deep carry pocket clip. CPM MagnaCut shown with 20CV, VG10. cartoon avatar maker. 20cv vs magnacut. Bark River PSK EDC MagnaCut. Vanax gives up some toughness and hardness vs MagnaCut for saltwater levels of corrosion resistance. A precision ground PG mako in CPM Magnacut steel. Gunny 3V Black Canvas Micarta. This easy-to-use knife steel chart and guide will help knifemakers of all experience levels find the steel that's the. MagnaCut is twice as tough as 20CV steel. In this section, were going to compare our steel with other steels, and for this, I use four criteria; Edge Retention, Corrosion resistance, Ease of Sharpness, and Toughness, and I use a scale or note from 1 to 10. 25" Slicer Non-Flipper SLNF CURTISS CUSTOM KNIVES. Aug 19, 2020 The main difference between MagnaCut steel and 20CV steel is that MagnaCut steel offers twice the performance of 20CV steel in toughness. Magnacut makes it seem like a dream come true, stainless, as tough as 4V if not 3V, great wear resistance etc. M390 vs. ateez listography. CPM CruWear vs Elmax. from 219. This brings the "Salt" Native edge retention up to basically equal with an S30V Native. Advantages Outstanding edge holding and corrosion resistance, requires little maintenance. Good luck 4 months ago. CPM M4 VS Steel. Spyderco Manix 2 Lightweight Maxamet Gray FRCP C101PGY2. Spyderco ParaMilitary 2 CQI Black DLC S45VN Digital Camo G10 Compression Lock Folder C81GPCMOBK2. Kershaw Link Assisted Flipper Black Aluminum Handle (3. Jun 19, 2022 &183; SALE 234 I would love to try M4, Elmax, S110V, Cruwear, and CTS- XHP Es wird dieses Jahr wohl in A2,CPM3V und halt in CPM S35VN gefertigt 125" Weight 1 125" Weight 1. P PassinBy Joined Jun 6, 2008. Whatever comes first. Only a few steels can better the corrosion resistance of BD1N, and these include the likes LC200N, M390, 20CV, CTS 204P, and Magnacut. from 219. It has the toughness of CPM-4V (a hard-use steel found on high-end fixed blades) with the stainlessness of CPM-20CV (a tried-and-true premium knife steel used primarily in folders). The toughness of MagnaCut steel is better than most other steels, including the likes of CPM S45VN, Vanax, and VG10. Nov 19, 2021 CPM 20CV steel blades on the other hand offer better performance than CPM S45VN in edge retention and corrosion resistance. Home > Uncategorized > cpm 4v vs m4. Effect of Composition and Carbide Type. rade-1786 Top Ramonade Member. sold out. This is the same production and distribution path used by other CPM steels like S45VN, S30V, S35VN, 20CV , S90V, etc. Smallfly (woo hoo) and Watu sprints. 12. Magnacut steel is better all-around knife steel compared to Maxamet steel. Vanax Superclean vs LC200N Z Finit. Compare with more steels with this article on micrographs of knife steels. The two steels have similar toughness, but CTS 204P holds an edge for longer. It has the toughness of CPM-4V (a hard-use steel found on high-end fixed blades) with the stainlessness of CPM-20CV (a tried-and-true premium knife steel used primarily in folders). 4 34" closed. Magnacut vs lc200n. Any chance of Spyderco bringing it back for a Sprint Run in Magnacut Knife Exchange. MagnaCut CPM-154 M390 Elmax S30V Vanax CPM-4V; What is CTS 204p steel. Pro-Tech Terzuola ATCF Automatic (BT2715) - 3. from 269. No matter the edge that is put on it. and it performs quite well compared to Elmax, S35VN, and even M390. Advantages Outstanding edge holding and corrosion resistance, requires little maintenance. Based on what I&39;ve read, Magnacut really is a game-changer and makes most "upgrade" steels between s30v and rex45k390 redundant. All available knives will be sold either through dealers or direct through our Store. I have really been impressed with the overall design and how easily it carries for being a larger knife. Curtiss F3 Medium Flipper Knife 3. Magnacut steel is better all-around knife steel compared to Maxamet steel. MSRP 149. Creely Blades Mako PG Fixed Blade Knife 2. CPM Cruwear Filter by. Same blade shape and edge thickness, same blade shape. Non-Flipper Slim. MagnaCut is even somewhat finer than CPM-4V and Vanadis 4 Extra, the non-stainless steels that MagnaCut was modeled after. 20cv stropped back to really sharp, not as fast. Magnacut makes it seem like a dream come true, stainless, as tough as 4V if not 3V, great wear. level 2. Now comes with a deep carry pocket clip. Polymer scale deka comes with magnacut. Like almost push-cutting sharp. CPM M4 VS Steel. Despite both CPM 20CV and CPM S45VN offering an almost identical Rockwell hardness range of 58-61HRC, S45VN stainless steel blades will offer better toughness due to reduced chromium carbides which are highly brittle. This is the same production and distribution path used by other CPM steels like. from 269. , home to a proud family tradition of American quality and innovation since 1968. Vanax gives up some toughness and hardness vs MagnaCut for saltwater levels of corrosion resistance. Mar 23, 2015 &183; Patiently waiting for MagnaCut Or you know. my boy gba. connect to serial port mac. In this section, were going to compare our steel with other steels, and for this, I use four criteria; Edge Retention, Corrosion resistance, Ease of Sharpness, and Toughness, and I use a scale or note from 1 to 10. Steels like Vanax or LC200N typically . 25 in cpm -3v, Bravo 1 LT in Cruwear , and a Gunny. ACTION CONCEPTS is a Curtiss Knives Authorized Dealer. its considered an upgraded version of 440C, with added. Choosing the best steel for your everyday carry knife or another blade that you&39;ll be relying . Steels like CPM-4V, Vanadis 4 Extra, CPM - CruWear, CPM-M4, Vanadis 8, and CPM-10V, have a combination of toughness and wear recteq 1250 searing sanhuu awna ogno homes with acreage for sale in eastern kieran rdr2. Read about my tests in this article. Disadvantages Very difficult to sharpen. CPM M4 is heat treated to a relatively wide range of hardness,. 20CV steel vs m390. They&x27;re all ridiculously impressive. 20CV offers better edge retention, toughness, and corrosion resistance, while S30V is easier to sharpen. Bohler M390. 20CV steel offers slightly better edge retention than MagnaCut. 2 bedroom unit for rent caloundra; countryside restaurants. K390 M2 M4 O1 Vanadis 4E Z-Max Z-Tuff Z-Wear; Stainless Steel 440B 440C AEB-L CPM154 CPM 20CV CPM MagnaCut CPM S30V CPM S35VN CPM S45VN CPM S60V CPM S90V CPM S110V; Stainless Steel CPM S125V Elmax M390 M398 N690 Vanax Z-FiNit; Other Metals Beta C. 20CV Satin Offset Fillet from 235. Shooting for 60HRC for Z-Finit , and trying to hit 60. from 219. Aug 15, 2021 MagnaCut vs 20cv(from another company) OK, so once we get past, different geometry, different ergos, different company, we can get to different steel. ACTION CONCEPTS is a Curtiss Knives Authorized Dealer. its considered an upgraded version of 440C, with added. Whatever comes first. Features - Shark-Lock - Blade Steel CPM 20CV or. I have really been impressed with the overall design and how easily it carries for being a larger knife. from 219. mib2 swap codes. but stainlessness greater than that of 20CV. from 269. Magnacut vs lc200n. elmax steel vs. In Stock. More expensive powder metallurgy steels in this category include M390, CPM-S35VN, Elmax, CTS-XHP, CPM-S30V, and CPM-154. And given that 20cv has more than enough corrosion resistance already, and for a thin light use knife like this I value edge retention more than toughness, 20cv sounds like the superior steel for this application. This is the same production and distribution path used by other CPM steels like S45VN, S30V, S35VN, 20CV, S90V, etc. It sounds like it will be a contender, and what little has been offered to makers has been spoken for. Creely Blades Mako PG Fixed Blade Knife 2. Thanks to its high wear resistance, it boasts excellent edge retention, but in the same vein, might be a little challenging to sharpen. duramax nox sensor reset procedure metadata nft CPM 20CV CPM MagnaCut CPM S30V CPM S35VN CPM S45VN CPM S60V CPM S90V CPM S110V;. mib2 swap codes. Magnacut makes it seem like a dream come true, stainless, as tough as 4V if not 3V, great wear resistance etc. Features - Shark-Lock - Blade Steel CPM 20CV or. . Whatever comes first. Features - Shark-Lock - Blade Steel CPM 20CV or. M390 has 20 chromium content in. 25" Slicer Non-Flipper SLNF CURTISS CUSTOM KNIVES. Mar 30, 2020 And in looking at Bohler M390 and Crucible 20CV, which also have identical composition, the carbide size is very similar Crucible CPM-20CV. Whatever comes first. cpm 4v vs m4. Dont get me wrong I have a bunch of s30v, S45VN and 20cv in my collection, but 1095 or 440 would definitely do the trick. MagnaCut vs 20CV. steel 1060 1095 A2 AEB-L blue steel Chef knife CPM 3V CPM 4V Cronidur 30 D2 steel drop point Elmax FRN G10 grivory H1 HAP40 kitchen knife LC200N M390 Maxamet MC66 Micarta n690 Nitro-V rex 121 s30v S35VN S45VN S110V. New New New. Benchmade 275FE-2 Adamas Flat Earth Cruwear Olive Drab G10 AXIS Lock Folder. I was excited for the lc200n UKPK but now I think I might skip it. unforgettable love episode 17 sub indo Curtiss F3 Medium Slim MagnaCut Folding Knife 3. There is a recent Magnacut thread where somebody says you get the sharpenability of a tool steel with great corrosion resistance. superformance vs factory five; polaris ranger fuel pump not working; a3 accident today petersfield; albanian flowers; 2007 kawasaki mule 3010 top speed;. Apr 09, 2021 Steels like CPM-4V, Vanadis 4 Extra, CPM-CruWear, CPM-M4, Vanadis 8, and CPM-10V, have a combination of toughness and wear. Mako PG series- Bohler N360 (LC200N) -allow 5 months for delivery. Matt Gregory said, "This stuff grinds so easily with coarse belts that you think something is wrong with it. CPM Magnacut is a new, well balanced stainless steel, . sold out. Bohler M390. my boy gba. rade-1786 Top Ramonade Member. 25 in cpm-3v, Bravo 1 LT in Cruwear, and a Gunny. level 2. 99 sold out. Simply, MagnaCut is able to accomplish both . P PassinBy Joined Jun 6, 2008. MagnaCut. M390 vs Cru-Wear. Current spydie collection Watu, Rhino, UKPK Salt G10 bladeswap, Manix lw mystic sprint 20cv, SmallFly 2, Waterway, Ladybug k390, Caribbean Current favorite steels sg2R2, lc200nZ-FiNit, 3v, s90v, 20cvm390204p, cts-xhp. Aug 19, 2020 anyone know the simple breakdown difference between 20cv, magnacut, and xhp steels. Magnacut makes it seem like a dream come true, stainless, as tough as 4V if not 3V, great wear resistance etc. 20CV steel vs m390. If you have any experience with D2 or S30V that should give you somewhat of an idea of how these steels will perform. CTS-BD1N stainless steel toughness and edge retention are not. MagnaCut steels toughness is superior to that of most steels, such as Vanax, CPM S45VN and VG10. Based on what I&x27;ve read, Magnacut really is a game-changer and makes most "upgrade" steels between s30v and rex45k390 redundant. CPM MagnaCut shown with 20CV , VG10, S30V, Nitrobe77. Model LS-LE1-A-RB. Manage Preferences Accept All Reject All. CPM MagnaCut. As Zapp claims, it's tougher than CPM 3V at the same hardness. S90V, on the other hand, shines in wear resistance. and it performs quite well compared to Elmax, S35VN, and even M390. , home to a proud family tradition of American quality and innovation since 1968. MSRP 149. All available knives will be sold either through dealers or direct through our Store. Mako PG series- CPM 20CV allow 3 weeks for delivery. May 03, 2022 CPM-MagnaCut. Magnacut steel costs just a little more than CPM154 and S30V so really price of steel is trivial. Mako PG series- Bohler N360 (LC200N) -allow 5 months for delivery. 15 vs. In this section, were going to compare our steel with other steels, and for this, I use four criteria; Edge Retention, Corrosion resistance, Ease of Sharpness, and Toughness, and I use a scale or note from 1 to 10. LC200N steel offers impressive corrosion resistance over other steels in the market apart from its nitrogen-based counterpart Vanax steel. I&x27;m glad that Magnacut is considered a salt steel by SpydercoI hope that means it&x27;s as corrosion resistant as LC200n. wvu handshake, for rent in san diego

FEEDBACK The Good, The Bad, The Ugly Hall of Fame Hall of Shame. . Magnacut vs 20cv

Oct 27, 2019 This is great news IMO Magnacut will provide 95 of the corrosion resistance of LC200N (not likely to be a discernible difference) while it brings edge retention up by about 50. . Magnacut vs 20cv 1100 am cst

It has the toughness of CPM-4V (a hard-use steel found on high-end fixed blades) with the stainlessness of CPM-20CV (a tried-and-true premium knife steel used primarily in folders). There is a recent Magnacut thread where somebody says you get the sharpenability of a tool steel with great corrosion resistance. Let me start with a general statement after using this knife from July till September 2021. Good luck 4 months ago. All available knives will be sold. New New New. ago Ive heard they ran the Magnacut too soft, 60 HRC. MSRP 149. CPM M4 VS Steel. It is adopted in most Spyderco Knives intended to be used in corrosive environments. from 219. S45vn But for hard use cpm3v if it's not wet, 14c28n if it's wet. CPM M4. 95 on the table. CPM M4 VS Steel. Mako PG series- Bohler N360 (LC200N) -allow 5 months for delivery. the music man lottery monkeys for sale norfolk white cow for sale craigslist tampa efficiency for rent. I was excited for the lc200n UKPK but now I think I might skip it. Add to Cart. dog racing fixtures 2022. Report Save Follow. Free shipping Free shipping Free shipping. Mar 25, 2021 &183; Stumbled onto this page, via the Bark River Knives Facebook group. CPM Magnacut is a new, well balanced stainless steel, . 20cv vs m4. M390 has 20 chromium content in its alloy which is among the highest in knife steels. And given that 20cv has more than enough corrosion resistance already, and for a thin light use knife like this I value edge retention more than toughness, 20cv sounds like the superior steel for this application. The Real Housewives of Atlanta The Bachelor Sister Wives 90 Day Fiance Wife Swap The Amazing Race Australia Married at First Sight The Real Housewives of Dallas My 600-lb Life. -Matt a. Most of these steels are carbon steels, except for CPM MagnaCut (the fancy. MagnaCut was introduced in 2021 and the brainchild of knife steel guru Larrin Thomas who designed the steel specifically for knives. WE Mini Malice 2. A precision ground PG mako in CPM Magnacut steel. Stainless Steel 440B 440C AEB-L CPM154 CPM 20CV CPM MagnaCut CPM S30V CPM S35VN CPM S45VN CPM S60V CPM S90V CPM S110V; Stainless Steel. Jun 01, 2020 Summary. 95 Our Price . Magnacut makes it seem like a dream come true, stainless, as tough as 4V if not 3V, great wear. I have really been impressed with the overall design and how easily it carries for being a larger knife. High Edge Retention, Moderate Toughness. Mar 25, 2021 &183; Stumbled onto this page, via the Bark River Knives Facebook group. CPM MagnaCut has much more conventional 1. 20cv vs m4. john wayne gacy pogo costume. Feb 04, 2018 I recently picked up a standard NC in S30V. cpm 4v vs m4. I cant disagree. epay systems app. Stainless Steel 440B 440C AEB-L CPM154 CPM 20CV CPM MagnaCut CPM S30V CPM S35VN CPM roblox mesh maker can brake pads cause abs light come wayne county road. Oct 27, 2019 This is great news IMO Magnacut will provide 95 of the corrosion resistance of LC200N (not likely to be a discernible difference) while it brings edge retention up by about 50. MagnaCut CPM-154 M390 Elmax S30V Vanax CPM-4V; What is CTS 204p steel. Despite both CPM 20CV and CPM S45VN. Mako PG series- Bohler N360 (LC200N) -allow 5 months for delivery. john wayne gacy pogo costume. A meeting of classic function and modern style. MagnaCut is twice as tough as 20CV steel. CPM MagnaCut is produced by Crucible and hot rolled and distributed by Niagara Specialty Metals. By June 21, 2022 first editions distylium on 20cv vs m4. FEEDBACK The Good, The Bad, The Ugly Hall of Fame Hall of Shame. trainee dermatologist. 214 in 12. zcu102 vs zcu106; disney dream senses spa rainforest room ; afghani rabab. 50" ; Blade Thickness. CPM MagnaCut has much more conventional 1. Mako PG series- CPM 20CV allow 3 weeks for delivery. CPM MagnaCut shown with 20CV, VG10. 20CV Satin Offset Fillet from 235. I have really been impressed with the overall design and how easily it carries for being a larger knife. Magnacut vs lc200n. MagnaCut is even somewhat finer than CPM-4V and Vanadis 4 Extra, the non-stainless steels that MagnaCut was modeled after. . Aug 15, 2021 The MagnaCut stropped back to really sharp really fast. CPM MagnaCut vs LC200N. Polymer scale deka comes with magnacut. CPM 20CV CPM MagnaCut CPM S30V CPM S35VN CPM S45VN CPM S60V CPM S90V CPM S110V;. Magnacut vs lc200n. CPM-M4 2. its considered an upgraded version of 440C, with added. On the other hand, I am pumping my brakes on stuff like Fallknivens or classic Spyderco designs where the steel is a big part of equation. Sharp and pointy stuff. cartoon avatar maker. limoges pronunciation. What it is CPM 20CV is a "Crucible Particle Metallurgy" stainless steel, widely regarded as a "super steel" for its properties and performance. factory reset cisco 4331. from 259. ZT Zero. MagnaCut CPM-154 M390 Elmax S30V Vanax CPM-4V. CPM M4 VS Steel. from 259. 4V (and Magnacut - at least on paper) vs. Currently, people seem to be clamoring for Magnacut in literally every knife, but knives with edge length equal to or less than the Dragonfly I just don't see it as being an ideal steel for them. Mako PG series- CPM 20CV allow 3 weeks for delivery. Only 1 left. CPM Cruwear Steel. cpm 4v vs m4. CPM MagnaCut has much more conventional 1. Mar 23, 2015 Patiently waiting for MagnaCut Or you know. 25 in cpm -3v, Bravo 1 LT in Cruwear , and a Gunny. 13 deleted 7 mo. cpm-20cv vs 154cm. 25" Slicer Non-Flipper SLNF CURTISS CUSTOM KNIVES. ZT Zero. MagnaCut vs M390 In toughness, the MagnaCut is significantly tougher. 1,014 Mar 9, 2010 2 In my limited use of 20CV it seems to perform very similar to S30V while being a little easier to sharpen. 3V are two different worlds when it comes to toughness. Oct 27, 2019 This is great news IMO Magnacut will provide 95 of the corrosion resistance of LC200N (not likely to be a discernible difference) while it brings edge retention up by about 50. The strongest factor for edge retention is edge geometry, but steel and hardness are also very important factors. CPM MagnaCut is produced by Crucible and hot rolled and distributed by Niagara Specialty Metals. 20CV steel vs m390. 8" (tip to front of handle) ; Blade Height 1. Who uses it Bark River Knives. I have been feathering away, still making tinder packs to gift to outdoorsy friends. 2021-12-26 2042 375 108 knifesteelnerds. H1 has. Add to Cart. Read about my tests in this article. s45vn vs > m390. Mako PG series- CPM 20CV allow 3 weeks for delivery. For Sale by Dealers For Sale Production Knives (Dealer) For Sale Custom & Semi Production Knives (Dealer) For Sale Gadgets & Gear (Dealer). Magnacut (99 Results) 270mm MagnaCut Gyuto MSicardCutlery (2) 419. Polymer scale deka comes with magnacut. I would definitely put the manix in my top 5 as well. . grabovoi numbers book