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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 396 · 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. 1.7?4 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  2. 2.Take 99 and take away the sum of its digits. What do you get?
  3. 3.Take 13 and take away the sum of its digits. What do you get?
  4. 4.Take 24 and take away the sum of its digits. What do you get?
  5. 5.Take 11 and take away the sum of its digits. What do you get?
  6. 6.30?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.4?75 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.21?3 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.?802 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.32?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.76?7 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.Take 96 and take away the sum of its digits. What do you get?
  13. 13.3?77 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.1?21 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.3?95 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.?08 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.4?71 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.Take 17 and take away the sum of its digits. What do you get?
  19. 19.?535 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.1?4 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.13?4 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.?839 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.Take 98 and take away the sum of its digits. What do you get?
  24. 24.27?6 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.60?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.?233 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.Take 51 and take away the sum of its digits. What do you get?
  28. 28.472? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.Take 31 and take away the sum of its digits. What do you get?
  30. 30.?244 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.Take 55 and take away the sum of its digits. What do you get?
  32. 32.45?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.43?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.?712 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.Take 91 and take away the sum of its digits. What do you get?
  36. 36.5?4 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.?035 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.Take 52 and take away the sum of its digits. What do you get?
  39. 39.Take 86 and take away the sum of its digits. What do you get?
  40. 40.Take 72 and take away the sum of its digits. What do you get?

Answer key

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

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