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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 259 · 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. 1.23?7 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  2. 2.46?3 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.144? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.?885 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.?580 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.Take 72 and take away the sum of its digits. What do you get?
  7. 7.4?63 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.1?24 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.Take 85 and take away the sum of its digits. What do you get?
  10. 10.10? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.33?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.Take 48 and take away the sum of its digits. What do you get?
  13. 13.87? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.7?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.40?9 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.Take 68 and take away the sum of its digits. What do you get?
  17. 17.770? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.Take 14 and take away the sum of its digits. What do you get?
  19. 19.Take 78 and take away the sum of its digits. What do you get?
  20. 20.15? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.5?84 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.Take 17 and take away the sum of its digits. What do you get?
  23. 23.1?29 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.154? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.?712 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.Take 27 and take away the sum of its digits. What do you get?
  27. 27.Take 21 and take away the sum of its digits. What do you get?
  28. 28.?490 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.5?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.67?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.Take 81 and take away the sum of its digits. What do you get?
  32. 32.36?3 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.Take 60 and take away the sum of its digits. What do you get?
  34. 34.Take 32 and take away the sum of its digits. What do you get?
  35. 35.Take 95 and take away the sum of its digits. What do you get?
  36. 36.263? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.Take 83 and take away the sum of its digits. What do you get?
  38. 38.Take 96 and take away the sum of its digits. What do you get?
  39. 39.?438 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.31?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?

Answer key

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

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