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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 649 · 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 89 and take away the sum of its digits. What do you get?
  2. 2.1?47 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.Take 70 and take away the sum of its digits. What do you get?
  4. 4.50?4 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.Take 51 and take away the sum of its digits. What do you get?
  6. 6.2?10 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.65?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.7?56 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.Take 68 and take away the sum of its digits. What do you get?
  10. 10.7?64 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.Take 15 and take away the sum of its digits. What do you get?
  12. 12.?080 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.33?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.41?7 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.Take 72 and take away the sum of its digits. What do you get?
  16. 16.Take 96 and take away the sum of its digits. What do you get?
  17. 17.Take 55 and take away the sum of its digits. What do you get?
  18. 18.4?69 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.Take 17 and take away the sum of its digits. What do you get?
  20. 20.Take 85 and take away the sum of its digits. What do you get?
  21. 21.103? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.3?3 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.Take 13 and take away the sum of its digits. What do you get?
  24. 24.4?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.Take 36 and take away the sum of its digits. What do you get?
  26. 26.?386 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.58?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.2?18 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.366? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.?304 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.Take 37 and take away the sum of its digits. What do you get?
  32. 32.?659 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.425? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.Take 91 and take away the sum of its digits. What do you get?
  35. 35.854? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.Take 49 and take away the sum of its digits. What do you get?
  37. 37.133? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.Take 20 and take away the sum of its digits. What do you get?
  39. 39.?23 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.27?4 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. 6
  3. 63
  4. 9
  5. 45
  6. 6
  7. 7
  8. 9
  9. 54
  10. 1
  11. 9
  12. 1
  13. 7
  14. 6
  15. 63
  16. 81
  17. 45
  18. 8
  19. 9
  20. 72
  21. 5
  22. 3
  23. 9
  24. 5
  25. 27
  26. 1
  27. 5
  28. 7
  29. 3
  30. 2
  31. 27
  32. 7
  33. 7
  34. 81
  35. 1
  36. 36
  37. 2
  38. 18
  39. 4
  40. 5

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