Mental Arithmetic Book 7 Tricks Vol 2

Can you multiply 35x35 in your head? That is, can you square the number 35?There's a mental math trick so that you can easily square any number ending in 5. Here's how the trick works.Look at the first digit of 35, which is the number 3. We add one to that number, 4, and then multiply those two numbers together. So we have 3x4 = 12, and these are the leading digits of the answer.Now we just write 25 as the last two digits, so we get 1225. And that's it! We have calculated 35 squared is 1,225 in an amazingly simple way!Math does not have to be hard. The Best Mental Math Tricks is a collection of methods that can help you become a lightning calculator. You will learn how to solve daily problems like calculating percentages and figuring out which day your birthday is every year. Then you will learn how to square numbers, multiply numbers, divide numbers, and even solve complex problems like calculating the cube root of numbers in your head!Each method is explained in detail with numerous examples. Every method is mathematically justified with a formal proof. Each section also contains practice problems accompanied with complete solutions so you can try the method and check your work.