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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 89 · 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.?589 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  2. 2.46?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.Take 18 and take away the sum of its digits. What do you get?
  4. 4.398? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.?02 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.5?34 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.765? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.Take 87 and take away the sum of its digits. What do you get?
  9. 9.4?04 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.?79 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.Take 72 and take away the sum of its digits. What do you get?
  12. 12.1?97 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.Take 83 and take away the sum of its digits. What do you get?
  14. 14.Take 47 and take away the sum of its digits. What do you get?
  15. 15.797? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.14?7 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.Take 97 and take away the sum of its digits. What do you get?
  18. 18.665? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.?393 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.Take 54 and take away the sum of its digits. What do you get?
  21. 21.Take 48 and take away the sum of its digits. What do you get?
  22. 22.Take 95 and take away the sum of its digits. What do you get?
  23. 23.73? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.693? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.?151 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.73?3 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.754? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.?773 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.Take 16 and take away the sum of its digits. What do you get?
  30. 30.Take 20 and take away the sum of its digits. What do you get?
  31. 31.8?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.Take 90 and take away the sum of its digits. What do you get?
  33. 33.88? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.475? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.3?05 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.?30 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.Take 40 and take away the sum of its digits. What do you get?
  38. 38.?686 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.?81 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.Take 86 and take away the sum of its digits. What do you get?

Answer key

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

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