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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 51 · 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. 2.40?3 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.?851 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.?58 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.51? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.Take 66 and take away the sum of its digits. What do you get?
  7. 7.Take 31 and take away the sum of its digits. What do you get?
  8. 8.?96 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.89?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.4?53 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.?484 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.Take 70 and take away the sum of its digits. What do you get?
  13. 13.24?3 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. 15.8?57 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.Take 54 and take away the sum of its digits. What do you get?
  17. 17.7?80 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.234? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.490? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.34?3 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.1?79 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.Take 16 and take away the sum of its digits. What do you get?
  23. 23.648? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.?779 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.2?34 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.Take 43 and take away the sum of its digits. What do you get?
  27. 27.Take 20 and take away the sum of its digits. What do you get?
  28. 28.?431 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.5?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.Take 14 and take away the sum of its digits. What do you get?
  31. 31.?478 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.Take 34 and take away the sum of its digits. What do you get?
  33. 33.?651 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.8?08 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.Take 87 and take away the sum of its digits. What do you get?
  36. 36.Take 28 and take away the sum of its digits. What do you get?
  37. 37.?04 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.Take 89 and take away the sum of its digits. What do you get?
  39. 39.475? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.Take 53 and take away the sum of its digits. What do you get?

Answer key

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

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