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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 297 · 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.?022 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  2. 2.39?7 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.Take 32 and take away the sum of its digits. What do you get?
  4. 4.Take 98 and take away the sum of its digits. What do you get?
  5. 5.34?3 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.Take 50 and take away the sum of its digits. What do you get?
  7. 7.Take 99 and take away the sum of its digits. What do you get?
  8. 8.Take 29 and take away the sum of its digits. What do you get?
  9. 9.Take 76 and take away the sum of its digits. What do you get?
  10. 10.Take 17 and take away the sum of its digits. What do you get?
  11. 11.?474 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.Take 23 and take away the sum of its digits. What do you get?
  13. 13.530? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.Take 58 and take away the sum of its digits. What do you get?
  15. 15.1?10 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.?94 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.8?11 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.1?61 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.Take 61 and take away the sum of its digits. What do you get?
  20. 20.?043 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.3?73 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.Take 89 and take away the sum of its digits. What do you get?
  23. 23.?548 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.3?46 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.67?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.Take 71 and take away the sum of its digits. What do you get?
  27. 27.326? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.71?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.?27 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.Take 67 and take away the sum of its digits. What do you get?
  31. 31.Take 52 and take away the sum of its digits. What do you get?
  32. 32.2?49 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.Take 77 and take away the sum of its digits. What do you get?
  34. 34.?38 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.10?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.?12 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.762? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.?458 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.7?65 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.Take 30 and take away the sum of its digits. What do you get?

Answer key

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

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