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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 12 · 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 23 and take away the sum of its digits. What do you get?
  2. 2.1?48 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.Take 40 and take away the sum of its digits. What do you get?
  4. 4.?372 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.?049 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.382? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.4?45 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.Take 67 and take away the sum of its digits. What do you get?
  9. 9.Take 36 and take away the sum of its digits. What do you get?
  10. 10.Take 11 and take away the sum of its digits. What do you get?
  11. 11.Take 68 and take away the sum of its digits. What do you get?
  12. 12.Take 54 and take away the sum of its digits. What do you get?
  13. 13.87?7 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.?500 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.?529 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.Take 14 and take away the sum of its digits. What do you get?
  17. 17.34?7 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.1?25 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.8?15 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.2?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.?66 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.464? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.32?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.72?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.Take 37 and take away the sum of its digits. What do you get?
  26. 26.Take 61 and take away the sum of its digits. What do you get?
  27. 27.?274 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.Take 38 and take away the sum of its digits. What do you get?
  29. 29.11?4 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.603? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.18?7 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.6?40 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.Take 85 and take away the sum of its digits. What do you get?
  34. 34.Take 51 and take away the sum of its digits. What do you get?
  35. 35.7?9 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.Take 76 and take away the sum of its digits. What do you get?
  37. 37.Take 22 and take away the sum of its digits. What do you get?
  38. 38.Take 45 and take away the sum of its digits. What do you get?
  39. 39.?690 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.803? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?

Answer key

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

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