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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 689 · 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 16 and take away the sum of its digits. What do you get?
  2. 2.Take 13 and take away the sum of its digits. What do you get?
  3. 3.6?72 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.Take 40 and take away the sum of its digits. What do you get?
  5. 5.Take 29 and take away the sum of its digits. What do you get?
  6. 6.Take 20 and take away the sum of its digits. What do you get?
  7. 7.498? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.Take 19 and take away the sum of its digits. What do you get?
  9. 9.Take 84 and take away the sum of its digits. What do you get?
  10. 10.7?94 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.18?6 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.17? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.?11 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.5?07 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.Take 59 and take away the sum of its digits. What do you get?
  16. 16.44?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.Take 66 and take away the sum of its digits. What do you get?
  18. 18.4?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.25?6 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.47?7 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.Take 78 and take away the sum of its digits. What do you get?
  22. 22.Take 45 and take away the sum of its digits. What do you get?
  23. 23.Take 55 and take away the sum of its digits. What do you get?
  24. 24.?83 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.Take 86 and take away the sum of its digits. What do you get?
  26. 26.582? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.844? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.Take 69 and take away the sum of its digits. What do you get?
  29. 29.Take 14 and take away the sum of its digits. What do you get?
  30. 30.8?65 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.2?90 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.79? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.569? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.?289 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.?833 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.?692 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.4?60 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.Take 50 and take away the sum of its digits. What do you get?
  39. 39.8?90 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.Take 98 and take away the sum of its digits. What do you get?

Answer key

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

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