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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 312 · 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.?409 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  2. 2.65?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.65?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.?848 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.559? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.?443 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.401? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.?037 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.315? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.2?07 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.Take 82 and take away the sum of its digits. What do you get?
  12. 12.1?80 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.6?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.Take 30 and take away the sum of its digits. What do you get?
  15. 15.1?71 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.510? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.3?42 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.67?6 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.Take 55 and take away the sum of its digits. What do you get?
  20. 20.Take 77 and take away the sum of its digits. What do you get?
  21. 21.Take 24 and take away the sum of its digits. What do you get?
  22. 22.?271 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.4?51 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.643? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.?482 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.101? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.Take 42 and take away the sum of its digits. What do you get?
  28. 28.41?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.53?4 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.?74 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.3?6 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.50?3 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.2?49 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.2?04 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.?383 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.?300 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.Take 58 and take away the sum of its digits. What do you get?
  38. 38.583? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.Take 95 and take away the sum of its digits. What do you get?
  40. 40.Take 74 and take away the sum of its digits. What do you get?

Answer key

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

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