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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 488 · 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. 1.33?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  2. 2.Take 26 and take away the sum of its digits. What do you get?
  3. 3.Take 63 and take away the sum of its digits. What do you get?
  4. 4.Take 31 and take away the sum of its digits. What do you get?
  5. 5.820? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.2?03 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.Take 89 and take away the sum of its digits. What do you get?
  8. 8.21?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.3?69 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.7?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.?964 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.72?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.?421 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.Take 18 and take away the sum of its digits. What do you get?
  15. 15.Take 25 and take away the sum of its digits. What do you get?
  16. 16.?440 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.Take 65 and take away the sum of its digits. What do you get?
  18. 18.Take 41 and take away the sum of its digits. What do you get?
  19. 19.?120 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.Take 66 and take away the sum of its digits. What do you get?
  21. 21.Take 42 and take away the sum of its digits. What do you get?
  22. 22.Take 27 and take away the sum of its digits. What do you get?
  23. 23.Take 12 and take away the sum of its digits. What do you get?
  24. 24.Take 96 and take away the sum of its digits. What do you get?
  25. 25.1?18 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.Take 40 and take away the sum of its digits. What do you get?
  27. 27.?231 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. 29.197? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.65?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.Take 43 and take away the sum of its digits. What do you get?
  32. 32.?884 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.Take 83 and take away the sum of its digits. What do you get?
  34. 34.267? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.Take 52 and take away the sum of its digits. What do you get?
  36. 36.789? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.?921 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.Take 81 and take away the sum of its digits. What do you get?
  39. 39.Take 37 and take away the sum of its digits. What do you get?
  40. 40.?77 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?

Answer key

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

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