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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 129 · 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. 1.3?31 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  2. 2.Take 32 and take away the sum of its digits. What do you get?
  3. 3.Take 66 and take away the sum of its digits. What do you get?
  4. 4.Take 52 and take away the sum of its digits. What do you get?
  5. 5.?440 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.59?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.266? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.69?7 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.Take 34 and take away the sum of its digits. What do you get?
  10. 10.?242 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.?626 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.Take 76 and take away the sum of its digits. What do you get?
  13. 13.Take 80 and take away the sum of its digits. What do you get?
  14. 14.Take 36 and take away the sum of its digits. What do you get?
  15. 15.1?46 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.2?24 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.424? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.Take 71 and take away the sum of its digits. What do you get?
  19. 19.?790 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.Take 49 and take away the sum of its digits. What do you get?
  21. 21.Take 28 and take away the sum of its digits. What do you get?
  22. 22.?645 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.3?01 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.27?9 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.249? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.?781 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.Take 57 and take away the sum of its digits. What do you get?
  28. 28.Take 87 and take away the sum of its digits. What do you get?
  29. 29.510? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.442? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.9?9 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.9?6 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.Take 70 and take away the sum of its digits. What do you get?
  34. 34.717? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.?25 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.18?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.7?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.1?72 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.17?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.1?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?

Answer key

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

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