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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 580 · 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 86 and take away the sum of its digits. What do you get?
  2. 2.Take 17 and take away the sum of its digits. What do you get?
  3. 3.Take 57 and take away the sum of its digits. What do you get?
  4. 4.2?52 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.5?00 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.3?53 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.479? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.201? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.Take 15 and take away the sum of its digits. What do you get?
  10. 10.Take 40 and take away the sum of its digits. What do you get?
  11. 11.?68 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.Take 77 and take away the sum of its digits. What do you get?
  13. 13.Take 45 and take away the sum of its digits. What do you get?
  14. 14.Take 52 and take away the sum of its digits. What do you get?
  15. 15.24?6 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.257? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.70?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.28?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.Take 19 and take away the sum of its digits. What do you get?
  20. 20.7?63 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.Take 58 and take away the sum of its digits. What do you get?
  22. 22.?800 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.360? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.226? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.Take 68 and take away the sum of its digits. What do you get?
  26. 26.Take 91 and take away the sum of its digits. What do you get?
  27. 27.39?3 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.Take 96 and take away the sum of its digits. What do you get?
  29. 29.Take 84 and take away the sum of its digits. What do you get?
  30. 30.?886 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.2?60 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.117? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.28? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.Take 21 and take away the sum of its digits. What do you get?
  35. 35.Take 33 and take away the sum of its digits. What do you get?
  36. 36.31?6 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.20?6 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.?631 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.2?50 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.140? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?

Answer key

  1. 72
  2. 9
  3. 45
  4. 9
  5. 4
  6. 7
  7. 7
  8. 6
  9. 9
  10. 36
  11. 4
  12. 63
  13. 36
  14. 45
  15. 6
  16. 4
  17. 1
  18. 7
  19. 9
  20. 2
  21. 45
  22. 1
  23. 9
  24. 8
  25. 54
  26. 81
  27. 3
  28. 81
  29. 72
  30. 5
  31. 1
  32. 9
  33. 8
  34. 18
  35. 27
  36. 8
  37. 1
  38. 8
  39. 2
  40. 4

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