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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 548 · 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 19 and take away the sum of its digits. What do you get?
  2. 2.?00 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.8?30 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.Take 51 and take away the sum of its digits. What do you get?
  5. 5.3?73 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.2?63 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.Take 78 and take away the sum of its digits. What do you get?
  8. 8.446? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.Take 21 and take away the sum of its digits. What do you get?
  10. 10.?670 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.322? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.Take 25 and take away the sum of its digits. What do you get?
  13. 13.Take 43 and take away the sum of its digits. What do you get?
  14. 14.Take 36 and take away the sum of its digits. What do you get?
  15. 15.Take 31 and take away the sum of its digits. What do you get?
  16. 16.Take 39 and take away the sum of its digits. What do you get?
  17. 17.?646 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.895? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.?281 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.4?01 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.8?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.113? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.Take 34 and take away the sum of its digits. What do you get?
  24. 24.?631 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.1?4 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.Take 41 and take away the sum of its digits. What do you get?
  27. 27.?741 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.?013 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.?434 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.89?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.7?58 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.53?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.Take 23 and take away the sum of its digits. What do you get?
  34. 34.?802 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.Take 46 and take away the sum of its digits. What do you get?
  36. 36.28?6 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.453? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.?338 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.?219 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.Take 58 and take away the sum of its digits. What do you get?

Answer key

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

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