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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 352 · 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 28 and take away the sum of its digits. What do you get?
  2. 2.79?4 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.3?73 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.Take 22 and take away the sum of its digits. What do you get?
  5. 5.1?14 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.28?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.1?06 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.2?47 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.340? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.Take 73 and take away the sum of its digits. What do you get?
  11. 11.3?76 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.32?9 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.Take 96 and take away the sum of its digits. What do you get?
  14. 14.?299 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.5?52 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.1?56 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.11?6 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.860? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.?984 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.5?28 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.?661 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.Take 35 and take away the sum of its digits. What do you get?
  23. 23.8?85 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.Take 77 and take away the sum of its digits. What do you get?
  25. 25.?462 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.2?00 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.Take 81 and take away the sum of its digits. What do you get?
  28. 28.Take 70 and take away the sum of its digits. What do you get?
  29. 29.Take 94 and take away the sum of its digits. What do you get?
  30. 30.146? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.Take 84 and take away the sum of its digits. What do you get?
  32. 32.?87 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.81?4 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.Take 40 and take away the sum of its digits. What do you get?
  35. 35.?110 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.Take 55 and take away the sum of its digits. What do you get?
  37. 37.4?07 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.853? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.2?98 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.Take 19 and take away the sum of its digits. What do you get?

Answer key

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

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