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Cool and Fun Math

 π  (the greek letter, pi, pronounced "pie") is an irrational number, which means it CANNOT be written as a terminating decimal (like 3.14) or a fraction (like 22/7).  Both 3.14 and 22/7 are only approximations.π is defined as the ratio of the circumference of a circle to its radius. Click this link for a cool video someone else made showing why π is close to 22/7.Alternative Arithmetic Methods (I think these are easier ways to add, multiply, etc.)Does 2 = 1? I use algebra to prove 2 = 1. Can you find the mistake? Knowledge of algebra, including factoring and rational expressions and equations is key to understanding the problem.Moebius (Mobius) Strip: This is a video where you see me in person using paper, scissors, and tape, and discover how to make a Moebius strip, as well as some very cool things about it.Multiply by 11 the Easy WayMultiply by 5 the easy wayMultiply by 5 the easy way even when you have decimalsScratch Addition (scratchadd.mp4): Show a quick and easy way to add a column of single digit numbers using the Scratch or Dot Method. Multiply by 9 the easy way: This video shows you easy ways to multiply single digits by 9, and larger numbers when all the digits are the same, like 88888 x 9...really easy and fun to do!Numerals: Shows the original numerals and the code for how it was obvious what each numeral stood for.  These are referred to as the Arabic numerals, the Hindu numerals, Hindu-Arabic numerals and/or the Indian numerals.  I do not know the exact origins.Squaring numbers whose digits are all ones; fun pattern for multiplying numbers by themselves (squaring) if all its digits are 1....like 11 x 11 or 11111 x 11111, etc. Show your friends!Square Numbers that end in 5 such as 85 time 85, etc.This YouTube channel has some cool math tricks for easy calculations.Videos by othersCalculus: This is the Derivate Rag (a song about how to remember how to take derivatives)