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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 785 · 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 37 and take away the sum of its digits. What do you get?
  2. 2.4?34 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.?082 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.5?95 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.Take 55 and take away the sum of its digits. What do you get?
  6. 6.Take 86 and take away the sum of its digits. What do you get?
  7. 7.272? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.?780 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.Take 39 and take away the sum of its digits. What do you get?
  10. 10.86?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.21?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.?803 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.3?01 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.235? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.Take 54 and take away the sum of its digits. What do you get?
  16. 16.298? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.2?64 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.Take 23 and take away the sum of its digits. What do you get?
  19. 19.25?6 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.3?09 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.5?88 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.?859 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.8?6 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.?839 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.414? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.152? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.Take 99 and take away the sum of its digits. What do you get?
  28. 28.Take 78 and take away the sum of its digits. What do you get?
  29. 29.Take 24 and take away the sum of its digits. What do you get?
  30. 30.?052 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.2?81 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.Take 98 and take away the sum of its digits. What do you get?
  33. 33.554? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.Take 19 and take away the sum of its digits. What do you get?
  35. 35.?228 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.651? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.35? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.5?11 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.151? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.?388 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?

Answer key

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

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