Fun Facts About Math
- 111,111,111 x 111,111,111 = 12,345,678,987,654,321
- 142857 is a cyclic number, this means the numbers always appear in the same order but rotated around when multipled by any number from 1 to 6. 142857 * 2 = 285714 142857 * 3 = 428571 142857 * 4 = 571428 142857 * 5 = 714285 142857 * 6 = 857142.
- 6 is the smallest perfect number. A perfect number is an integer such that the sum of its proper divisors is equal to the integer itself: 6 = 1 + 2 + 3.
- An easy way to square any 2 digit number that ends in 5. The last 2 digits of the answer will be 25, the preceding digits will be N*(N+1) where N is the first digit of the number. For example 25x25: 2(2+1)=6. So 25x25=625.
- National Pi Day is March 14, at 1:59. (3/14 1:59).
- Pick a number. Any integer will do. Now if the number is even, divide it by 2; if the number is odd then multiply it by 3 and add 1. Keep doing this over and over. No matter what number you start with you will eventually get to the same series of numbers: 4,2,1,4,2,1,4,2,1...
- The only prime numbers that end in 2 or 5 are the numbers 2 and 5.
- Think of a positive number (keep it small so you can do the math in your head). Now do the following: 1. Square it. 2. Add the result to your original number. 3. Divide by your original number. 4. Add, oh I don't know, try 17. 5. Subtract your original number. 6. Divide by 6. Your answer will always be 3 regardless of the orginal number.
- To multiply by a 2-digit number by 11, all you have to is add the two digits and place the sum in between. Here are some examples: 32x11 = 352. See you add 3+2=5 and put the 5 between the 3 and the 2. Let's try another: 25X11=275.
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