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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 151 · 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.?254 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  2. 2.78?7 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.80?9 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.14? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.Take 92 and take away the sum of its digits. What do you get?
  6. 6.11?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.50? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.2?09 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.3?43 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.Take 71 and take away the sum of its digits. What do you get?
  11. 11.2?18 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.?770 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.39?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.1?78 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.Take 27 and take away the sum of its digits. What do you get?
  16. 16.Take 81 and take away the sum of its digits. What do you get?
  17. 17.1?65 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.?179 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.?824 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.53?9 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.4?31 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.?433 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.Take 68 and take away the sum of its digits. What do you get?
  24. 24.Take 90 and take away the sum of its digits. What do you get?
  25. 25.Take 22 and take away the sum of its digits. What do you get?
  26. 26.2?96 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.Take 69 and take away the sum of its digits. What do you get?
  28. 28.312? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.73?3 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.5?85 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.2?97 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.3?84 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.3?71 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.?660 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.44?3 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.Take 23 and take away the sum of its digits. What do you get?
  37. 37.56?6 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.3?19 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.Take 87 and take away the sum of its digits. What do you get?
  40. 40.Take 86 and take away the sum of its digits. What do you get?

Answer key

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

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