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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 998 · 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 41 and take away the sum of its digits. What do you get?
  2. 2.Take 91 and take away the sum of its digits. What do you get?
  3. 3.2?26 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.Take 28 and take away the sum of its digits. What do you get?
  5. 5.1?56 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.?019 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.Take 31 and take away the sum of its digits. What do you get?
  8. 8.288? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.?62 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.4?38 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.87?9 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.Take 99 and take away the sum of its digits. What do you get?
  13. 13.7?91 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.Take 34 and take away the sum of its digits. What do you get?
  15. 15.3?97 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.11?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.Take 35 and take away the sum of its digits. What do you get?
  18. 18.853? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.?363 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.Take 55 and take away the sum of its digits. What do you get?
  21. 21.3?9 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.Take 67 and take away the sum of its digits. What do you get?
  23. 23.30?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.?152 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.32?7 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.?024 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.Take 22 and take away the sum of its digits. What do you get?
  28. 28.8?49 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.7?49 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.?246 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.?482 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.85?9 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.Take 12 and take away the sum of its digits. What do you get?
  34. 34.260? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.836? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.Take 18 and take away the sum of its digits. What do you get?
  37. 37.Take 45 and take away the sum of its digits. What do you get?
  38. 38.Take 77 and take away the sum of its digits. What do you get?
  39. 39.Take 13 and take away the sum of its digits. What do you get?
  40. 40.Take 20 and take away the sum of its digits. What do you get?

Answer key

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

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