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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 532 · 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. 1.90? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  2. 2.1?13 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.?059 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.659? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.Take 78 and take away the sum of its digits. What do you get?
  6. 6.64? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.?266 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.?402 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.6?58 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.8?95 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.Take 43 and take away the sum of its digits. What do you get?
  12. 12.525? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.Take 12 and take away the sum of its digits. What do you get?
  14. 14.Take 61 and take away the sum of its digits. What do you get?
  15. 15.Take 59 and take away the sum of its digits. What do you get?
  16. 16.Take 16 and take away the sum of its digits. What do you get?
  17. 17.42?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.Take 88 and take away the sum of its digits. What do you get?
  19. 19.?777 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.Take 96 and take away the sum of its digits. What do you get?
  21. 21.51?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.Take 72 and take away the sum of its digits. What do you get?
  23. 23.1?19 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.862? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.Take 63 and take away the sum of its digits. What do you get?
  26. 26.Take 14 and take away the sum of its digits. What do you get?
  27. 27.6?07 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.Take 42 and take away the sum of its digits. What do you get?
  29. 29.Take 35 and take away the sum of its digits. What do you get?
  30. 30.1?73 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.?985 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.12?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.4?39 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.?15 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.Take 39 and take away the sum of its digits. What do you get?
  36. 36.?451 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.?736 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.Take 71 and take away the sum of its digits. What do you get?
  39. 39.6?45 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.Take 38 and take away the sum of its digits. What do you get?

Answer key

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

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