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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 528 · 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. 1.631? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  2. 2.7?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.Take 58 and take away the sum of its digits. What do you get?
  4. 4.2?87 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.Take 61 and take away the sum of its digits. What do you get?
  6. 6.6?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.2?21 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.13? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.?977 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.2?79 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.32?9 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.11?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.?902 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.42?3 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.Take 37 and take away the sum of its digits. What do you get?
  16. 16.?130 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.495? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.?68 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.Take 79 and take away the sum of its digits. What do you get?
  20. 20.40?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.Take 96 and take away the sum of its digits. What do you get?
  22. 22.302? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.4?78 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.8?21 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.80?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.1?49 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.?90 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.5?6 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.Take 11 and take away the sum of its digits. What do you get?
  30. 30.Take 15 and take away the sum of its digits. What do you get?
  31. 31.380? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.?860 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.5?60 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.501? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.Take 28 and take away the sum of its digits. What do you get?
  36. 36.816? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.?20 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.Take 72 and take away the sum of its digits. What do you get?
  39. 39.Take 17 and take away the sum of its digits. What do you get?
  40. 40.Take 40 and take away the sum of its digits. What do you get?

Answer key

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

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