Simple and useful math tricks
1. Memorizing Pi To remember the first seven digits of pi , count the number of letters in each word of the sentence: "How I wish I could calculate pi." This becomes 3.141592. 2. Contains the Digits 1, 2, 4, 5, 7, 8 Select a number from 1 to 6. Multiply the number by 9. Multiply it by 111. Multiply it by 1001. Divide the answer by 7. The number will contain the digits 1, 2, 4, 5, 7, and 8. Example: The number 6 yields the answer 714285. 3. Multiply Large Numbers in Your Head To easily multiply two double-digit numbers, use their distance from 100 to simplify the math: Subtract each number from 100. Add these values together. 100 minus this number is the first part of the answer. Multiply the digits from Step 1 to get the second part of the answer. 4. Super Simple Divisibility Rules You've got 210 pieces of pizza and want to know whether or not you can split them evenly within your group. Rather than whip out the calculator, use these simple shortcuts to do the math