MATH MAGIC

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Simple math tricks and hints. :)

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MATH MAGIC

  1. 1. 20August 2013 MATH MAGIC 20 August 2013
  2. 2. MULTIPLICATION TRICKS
  3. 3. CROSS- MULPLICATION 14 X 12
  4. 4. First, to get the last digit in the answer, multiply the two numbers on the right. Write the answer, as the rightmost digit in the problem’s answer.
  5. 5. 2x4=8 14 X 12 8
  6. 6. Now, get the middle digit, cross- multiply both sets of numbers, and then add the together.
  7. 7. 1 x 2 = 2 1 x 4 = 4 6 14 X 12 68
  8. 8. Lastly to get the last digit, simply multiply the left digits.
  9. 9. 1 x 1= 1 14 X 12 168
  10. 10. TRY! 28 X 23 In this case, we will do the carrying procedure.
  11. 11. COMPLEMENTARY MULTIPLICATION 96 x 94
  12. 12. First, subtract both numbers in 100 and list the difference. 100 - 96 = 4 100 - 94 = 6
  13. 13. Second step is to subtract diagonally. You will notice there that they will give the same answer, and this will be your base number.
  14. 14. 96 – 6 = 90 94 – 4 = 90
  15. 15. 96 x 94 90
  16. 16. Third, multiply the two numbers we got by figuring the difference between the original numbers and 100. 4 x 6 = 24
  17. 17. •Lastly, write it to the right of the base number. 96 x 94 9,024
  18. 18. •If the number are larger than 100, add the difference instead of subtracting. Ex. 103 x 107
  19. 19. 103 – 100 = 3 107 – 100 = 7 103 + 7 = 110 107 + 3 = 110
  20. 20. •You will arrive with same answer then write it as the base number. 103 x 107 110
  21. 21. •Multiply the 3 and 7, then write it as the base number. 3 x 7 = 21
  22. 22. 103 x 107 11,021
  23. 23. This method is applicable also in numbers around 50. Ex. 46 x 44
  24. 24. MULTIPLYING BY 11 18 X 11
  25. 25. •Add the two digits and insert the sum between the digits. 1 + 8 = 9
  26. 26. 18 X 11 198
  27. 27. 99 X 11 In case that you got a two-digit number, add that numbers’ left digit to the digit in the original number.
  28. 28. 9 + 9 = 18 99 X 11 1,089
  29. 29. SQUARING TRICKS
  30. 30. Squaring a number around 100 If the number falls under 100 and above 50, you simply figure the difference between 100 and the number. 96²
  31. 31. •Subtract the difference from the number being squared, and write the answer as the first digits in your answer. 100 – 96 = 4
  32. 32. 96² - 4 92 base number 92(00)
  33. 33. •Take the difference between 100 and the number being squared and square. 100 – 96 = 4 4² = 16
  34. 34. •Place that number after the base number and you have the answer. 96² = 9,216
  35. 35. If the number to be squared is more than 100, add the difference to the number.
  36. 36. Squaring numbers that ends in 5 Any number that ends in 5 is easy to square to start with, you know that 5 x 5 = 25, so the answer will automatically end in 25. Ex. 35²
  37. 37. •Add 1 to the first digit, ignore the rest at the number. 1 + 3(5) 4
  38. 38. •Multiply the result to the first digit of the original number. This result is the first part of the answer. 4 x 3 = 12
  39. 39. 12 with 25 makes 1, 225. Try! 85² 115² 65²
  40. 40. SHORTCUT AND HELPFUL HINTS 18 X 101 = 1,818 84 X 101 = 8,484 97 X 101 = 9,797 102 X 101 = 10,302 621 X 101 = 62,721
  41. 41. Thank you!

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