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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 449 · 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.?404 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  2. 2.71?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.Take 24 and take away the sum of its digits. What do you get?
  4. 4.Take 34 and take away the sum of its digits. What do you get?
  5. 5.7?34 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.4?07 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.?875 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.Take 84 and take away the sum of its digits. What do you get?
  9. 9.7?59 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.Take 29 and take away the sum of its digits. What do you get?
  11. 11.Take 51 and take away the sum of its digits. What do you get?
  12. 12.Take 28 and take away the sum of its digits. What do you get?
  13. 13.82?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.89?9 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.Take 12 and take away the sum of its digits. What do you get?
  16. 16.Take 14 and take away the sum of its digits. What do you get?
  17. 17.468? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.44?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.762? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.?668 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.Take 70 and take away the sum of its digits. What do you get?
  22. 22.?311 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.Take 26 and take away the sum of its digits. What do you get?
  24. 24.4?41 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.?743 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.7?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.Take 48 and take away the sum of its digits. What do you get?
  28. 28.Take 94 and take away the sum of its digits. What do you get?
  29. 29.?426 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.1?32 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.Take 56 and take away the sum of its digits. What do you get?
  32. 32.410? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.?101 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.?70 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.11?6 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.837? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.406? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.172? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.Take 74 and take away the sum of its digits. What do you get?
  40. 40.?359 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?

Answer key

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

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