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Math Tricks

Math Tricks. Cathy Carter Shide. Write the last digit of your phone number Add two. Multiply by three. Subtract four. Add one more than the number you chose. Add five. Divide by four. Announce your result. x. x+2. 3(x+2) = 3x +6. 3x+6–4 = 3x + 2. 3x + 2 + (x+1) = 4x + 3.

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Math Tricks

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  1. Math Tricks Cathy Carter Shide

  2. Write the last digit of your phone number Add two. Multiply by three. Subtract four. Add one more than the number you chose. Add five. Divide by four. Announce your result. x x+2 3(x+2) = 3x +6 3x+6–4 = 3x + 2 3x + 2 + (x+1) = 4x + 3 4x+3+5 = 4x + 8

  3. Write the last digit of your phone number Add two. Multiply by three. Subtract four. Add one more than the number you chose. Add five. Divide by four. Announce your result. x x+2 3(x+2)=3x +6 3x+6-4=3x+2 3x+2+(x+1)= 4x+3 4x+3+5=4x+8 (4x+8)/4 = x+2 To figure the phone number take their number and subtract two.

  4. Three-Dice Trick – roll 3 dice • Multiply the number on one of the dice by 2 • Add 5 to the product • Multiply this result by 5 • Add a number from one of the other two dice • Now multiply by 10 • Add the third number • Subtract 250 – What do you see?

  5. Multiply the number on one of the dice by 2 Add 5 to the product Multiply this result by 5 Add a number from one of the other two dice Now multiply by 10 Add the third number Subtract 250 – What do you see? 2x 2x + 5 5 (2x + 5) = 10x +25 10x + 25 +y 10(10x + 25 + y) = 100x + 250 + 10 y 100 x + 250 + 10y + z 100 x + 10 y + z Three-Dice Trick – roll 3 dice

  6. Calculator Trick • Grab a calculator. (you won't be able to do this one in your head) • Key in the first three digits of your phone number (NOT the area code) • Multiply by 80 • Add 1 • Multiply by 250 • Add the last 4 digits of your phone number • Add the last 4 digits of your phone number again. • Subtract 250 • Divide number by 2

  7. Key in the first three digits of your phone number (NOT the area code) Multiply by 80 Add 1 Multiply by 250 Add the last 4 digits of your phone number Add the last 4 digits of your phone number again. Subtract 250 Divide number by 2 x 80x 80x +1 250(80x + 1) = 20,000x + 250 20,000x + 250 + y 20,000x + 250 + y + y = 20,000x + 250 + 2y 20,000x + 250 + 2y – 250 = 20,000x + 2y (20,000x + 2y)/2 10,000x + y (x is a 3 digit number and y is a 4 digit number) Calculator Trick • Grab a calculator. (you won't be able to do this one in your head)

  8. Find your Role Model • It is truly remarkable just how accurate this is! 1)  Pick your favorite number between 1 and 8 2)  Multiply your choice by 3 3)  Add 3 4)  Multiply again by 3   5) You'll get a 2 digit number.....maybe 42, for example 6) Add the digits together.  Example 4 and 2 = 6 • 1.Albert Einstein2. Billy Graham3. Mother Theresa4. Ronald Reagan5. Bill Gates 6. Gandhi 7. Bill Gaither8. Babe Ruth9. Cathy Shide10. Winston Churchill11. Barbara Walters 12. Dalai Lama

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