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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 4 · 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.Take 19 and take away the sum of its digits. What do you get?
  2. 2.Take 61 and take away the sum of its digits. What do you get?
  3. 3.?470 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.92? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.Take 48 and take away the sum of its digits. What do you get?
  6. 6.640? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.5?83 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.?564 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.?04 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.Take 63 and take away the sum of its digits. What do you get?
  11. 11.Take 16 and take away the sum of its digits. What do you get?
  12. 12.193? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.Take 98 and take away the sum of its digits. What do you get?
  14. 14.Take 44 and take away the sum of its digits. What do you get?
  15. 15.Take 24 and take away the sum of its digits. What do you get?
  16. 16.?512 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.Take 94 and take away the sum of its digits. What do you get?
  18. 18.2?62 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.Take 20 and take away the sum of its digits. What do you get?
  20. 20.21?4 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.Take 99 and take away the sum of its digits. What do you get?
  22. 22.84? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.Take 18 and take away the sum of its digits. What do you get?
  24. 24.Take 93 and take away the sum of its digits. What do you get?
  25. 25.Take 68 and take away the sum of its digits. What do you get?
  26. 26.3?12 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.?008 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.1?60 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.?05 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.?508 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.?577 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.?78 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.?073 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.Take 30 and take away the sum of its digits. What do you get?
  35. 35.?971 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.Take 41 and take away the sum of its digits. What do you get?
  37. 37.6?89 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.60?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.Take 65 and take away the sum of its digits. What do you get?
  40. 40.8?07 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?

Answer key

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

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