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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 706 · 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 98 and take away the sum of its digits. What do you get?
  2. 2.47?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.Take 21 and take away the sum of its digits. What do you get?
  4. 4.Take 70 and take away the sum of its digits. What do you get?
  5. 5.8?7 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.821? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.24?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.Take 84 and take away the sum of its digits. What do you get?
  9. 9.Take 11 and take away the sum of its digits. What do you get?
  10. 10.Take 75 and take away the sum of its digits. What do you get?
  11. 11.8?02 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.7?03 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.Take 26 and take away the sum of its digits. What do you get?
  14. 14.Take 24 and take away the sum of its digits. What do you get?
  15. 15.Take 77 and take away the sum of its digits. What do you get?
  16. 16.87?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.?815 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.Take 68 and take away the sum of its digits. What do you get?
  19. 19.72? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.6?25 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.Take 12 and take away the sum of its digits. What do you get?
  22. 22.Take 89 and take away the sum of its digits. What do you get?
  23. 23.Take 15 and take away the sum of its digits. What do you get?
  24. 24.563? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.?237 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.?875 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.?650 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.492? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.Take 43 and take away the sum of its digits. What do you get?
  30. 30.Take 86 and take away the sum of its digits. What do you get?
  31. 31.73?4 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.Take 42 and take away the sum of its digits. What do you get?
  33. 33.Take 88 and take away the sum of its digits. What do you get?
  34. 34.?620 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.?062 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.Take 16 and take away the sum of its digits. What do you get?
  37. 37.?834 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.68?4 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.1?49 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.700? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?

Answer key

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

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