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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 901 · 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.?239 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  2. 2.Take 45 and take away the sum of its digits. What do you get?
  3. 3.668? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.Take 96 and take away the sum of its digits. What do you get?
  5. 5.?752 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.7?70 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.4?80 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.Take 68 and take away the sum of its digits. What do you get?
  9. 9.8?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.5?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.10? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.Take 89 and take away the sum of its digits. What do you get?
  13. 13.472? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.702? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.Take 52 and take away the sum of its digits. What do you get?
  16. 16.?93 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.78?6 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.684? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.?641 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.Take 55 and take away the sum of its digits. What do you get?
  21. 21.?376 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.18?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.Take 18 and take away the sum of its digits. What do you get?
  24. 24.80? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.9?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.29?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.1?20 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.Take 13 and take away the sum of its digits. What do you get?
  29. 29.Take 28 and take away the sum of its digits. What do you get?
  30. 30.Take 21 and take away the sum of its digits. What do you get?
  31. 31.?087 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.Take 23 and take away the sum of its digits. What do you get?
  33. 33.?025 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.344? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.679? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.Take 73 and take away the sum of its digits. What do you get?
  37. 37.Take 53 and take away the sum of its digits. What do you get?
  38. 38.5?31 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.2?92 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.2?70 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?

Answer key

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

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