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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 232 · 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 23 and take away the sum of its digits. What do you get?
  2. 2.Take 65 and take away the sum of its digits. What do you get?
  3. 3.?498 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.Take 89 and take away the sum of its digits. What do you get?
  5. 5.2?9 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.Take 33 and take away the sum of its digits. What do you get?
  7. 7.26?6 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.?848 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.?286 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.Take 94 and take away the sum of its digits. What do you get?
  11. 11.1?70 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.Take 79 and take away the sum of its digits. What do you get?
  13. 13.17? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.Take 54 and take away the sum of its digits. What do you get?
  15. 15.4?87 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.Take 11 and take away the sum of its digits. What do you get?
  17. 17.?572 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.70?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.110? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.51?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.7?64 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.Take 38 and take away the sum of its digits. What do you get?
  23. 23.?59 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.22?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.43?4 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.4?53 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.?329 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.67?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.Take 57 and take away the sum of its digits. What do you get?
  30. 30.4?28 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.1?99 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.8?41 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.3?70 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.Take 62 and take away the sum of its digits. What do you get?
  35. 35.2?61 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.3?7 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.?794 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.?911 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.210? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.3?97 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. 54
  3. 6
  4. 72
  5. 7
  6. 27
  7. 4
  8. 7
  9. 2
  10. 81
  11. 1
  12. 63
  13. 1
  14. 45
  15. 8
  16. 9
  17. 4
  18. 9
  19. 7
  20. 1
  21. 1
  22. 27
  23. 4
  24. 3
  25. 7
  26. 6
  27. 4
  28. 9
  29. 45
  30. 4
  31. 8
  32. 5
  33. 8
  34. 54
  35. 9
  36. 8
  37. 7
  38. 7
  39. 6
  40. 8

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