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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 524 · 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 20 and take away the sum of its digits. What do you get?
  2. 2.?181 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.7?10 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.Take 64 and take away the sum of its digits. What do you get?
  5. 5.44?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.?074 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.?592 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.13?3 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.?092 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.?964 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.?534 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.Take 56 and take away the sum of its digits. What do you get?
  13. 13.Take 54 and take away the sum of its digits. What do you get?
  14. 14.301? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.?115 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.Take 14 and take away the sum of its digits. What do you get?
  17. 17.855? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.?497 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.Take 36 and take away the sum of its digits. What do you get?
  20. 20.Take 89 and take away the sum of its digits. What do you get?
  21. 21.797? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.3?94 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.4?97 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.Take 98 and take away the sum of its digits. What do you get?
  25. 25.Take 75 and take away the sum of its digits. What do you get?
  26. 26.?044 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.3?56 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.Take 99 and take away the sum of its digits. What do you get?
  29. 29.?557 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.Take 83 and take away the sum of its digits. What do you get?
  31. 31.?69 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.Take 72 and take away the sum of its digits. What do you get?
  33. 33.2?52 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.?04 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.Take 80 and take away the sum of its digits. What do you get?
  36. 36.7?52 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.Take 91 and take away the sum of its digits. What do you get?
  38. 38.Take 51 and take away the sum of its digits. What do you get?
  39. 39.Take 66 and take away the sum of its digits. What do you get?
  40. 40.6?31 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?

Answer key

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

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