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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 434 · 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. 1.46? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  2. 2.Take 50 and take away the sum of its digits. What do you get?
  3. 3.?863 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.7?69 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.529? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.7?51 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.1?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.80? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.Take 40 and take away the sum of its digits. What do you get?
  10. 10.Take 55 and take away the sum of its digits. What do you get?
  11. 11.?644 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.23? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.Take 80 and take away the sum of its digits. What do you get?
  14. 14.38? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.711? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.?249 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.Take 44 and take away the sum of its digits. What do you get?
  18. 18.Take 53 and take away the sum of its digits. What do you get?
  19. 19.Take 23 and take away the sum of its digits. What do you get?
  20. 20.877? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.17?6 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.Take 99 and take away the sum of its digits. What do you get?
  23. 23.68?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.20?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.4?94 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.1?18 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.797? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.?13 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.70?9 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.8?30 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. 32.10?6 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.14?3 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.Take 82 and take away the sum of its digits. What do you get?
  35. 35.8?9 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.?781 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.58?7 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.27?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.77?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.?173 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?

Answer key

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

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