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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 35 · 40 questions
TalentJR

The trick (Digits add to the 9 table): Add the digits you can see. Find the next number in the 9 table (9, 18, 27 …) above that total. The hidden digit is the difference. (Any number minus its digit sum is in the 9 table too.)

NameDateTime takenScore ___ / 40
  1. 1.Take 36 and take away the sum of its digits. What do you get?
  2. 2.?37 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.37? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.6?7 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.Take 12 and take away the sum of its digits. What do you get?
  6. 6.2?37 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.545? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.553? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.Take 18 and take away the sum of its digits. What do you get?
  10. 10.Take 73 and take away the sum of its digits. What do you get?
  11. 11.Take 50 and take away the sum of its digits. What do you get?
  12. 12.4?12 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.6?72 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.3?48 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.Take 51 and take away the sum of its digits. What do you get?
  16. 16.5?52 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.Take 42 and take away the sum of its digits. What do you get?
  18. 18.?637 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.1?60 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.Take 74 and take away the sum of its digits. What do you get?
  21. 21.125? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.78?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.Take 21 and take away the sum of its digits. What do you get?
  24. 24.672? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.8?38 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.14?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.76?6 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.Take 82 and take away the sum of its digits. What do you get?
  29. 29.Take 79 and take away the sum of its digits. What do you get?
  30. 30.5?91 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.Take 98 and take away the sum of its digits. What do you get?
  32. 32.Take 65 and take away the sum of its digits. What do you get?
  33. 33.81?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.?949 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.?88 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.Take 77 and take away the sum of its digits. What do you get?
  37. 37.Take 91 and take away the sum of its digits. What do you get?
  38. 38.26?4 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.Take 32 and take away the sum of its digits. What do you get?
  40. 40.59?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?

Answer key

  1. 27
  2. 8
  3. 8
  4. 5
  5. 9
  6. 6
  7. 4
  8. 5
  9. 9
  10. 63
  11. 45
  12. 2
  13. 3
  14. 3
  15. 45
  16. 6
  17. 36
  18. 2
  19. 2
  20. 63
  21. 1
  22. 2
  23. 18
  24. 3
  25. 8
  26. 4
  27. 8
  28. 72
  29. 63
  30. 3
  31. 81
  32. 54
  33. 4
  34. 5
  35. 2
  36. 63
  37. 81
  38. 6
  39. 27
  40. 2

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