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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 685 · 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 52 and take away the sum of its digits. What do you get?
  2. 2.Take 24 and take away the sum of its digits. What do you get?
  3. 3.?484 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.494? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.Take 79 and take away the sum of its digits. What do you get?
  6. 6.Take 78 and take away the sum of its digits. What do you get?
  7. 7.Take 74 and take away the sum of its digits. What do you get?
  8. 8.Take 87 and take away the sum of its digits. What do you get?
  9. 9.389? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.23?9 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.?953 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.Take 58 and take away the sum of its digits. What do you get?
  13. 13.Take 96 and take away the sum of its digits. What do you get?
  14. 14.Take 71 and take away the sum of its digits. What do you get?
  15. 15.?159 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.?373 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.?079 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.4?98 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.4?51 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.225? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.?705 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.887? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.46?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.7?45 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.68?6 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.2?80 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.Take 12 and take away the sum of its digits. What do you get?
  28. 28.6?44 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.?825 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.50?9 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.59?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.74?3 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.Take 76 and take away the sum of its digits. What do you get?
  34. 34.Take 35 and take away the sum of its digits. What do you get?
  35. 35.792? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.2?51 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.6?9 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.Take 39 and take away the sum of its digits. What do you get?
  39. 39.7?92 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.?152 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?

Answer key

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

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