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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 70 · 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.?637 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  2. 2.Take 77 and take away the sum of its digits. What do you get?
  3. 3.?826 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.Take 44 and take away the sum of its digits. What do you get?
  5. 5.Take 62 and take away the sum of its digits. What do you get?
  6. 6.Take 72 and take away the sum of its digits. What do you get?
  7. 7.835? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.?850 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.Take 97 and take away the sum of its digits. What do you get?
  10. 10.2?21 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.78? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.6?46 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.17?7 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.49? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.258? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.Take 82 and take away the sum of its digits. What do you get?
  17. 17.8?04 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.73?3 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.Take 21 and take away the sum of its digits. What do you get?
  20. 20.87?9 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.866? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.31?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.Take 87 and take away the sum of its digits. What do you get?
  24. 24.1?48 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.325? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.Take 92 and take away the sum of its digits. What do you get?
  27. 27.7?65 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.4?67 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.?449 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.Take 51 and take away the sum of its digits. What do you get?
  31. 31.1?89 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.Take 70 and take away the sum of its digits. What do you get?
  33. 33.3?31 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.650? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.Take 17 and take away the sum of its digits. What do you get?
  36. 36.?63 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.501? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.21?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.6?73 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.58?9 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?

Answer key

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

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