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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 439 · 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. 1.3?47 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  2. 2.?205 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.Take 32 and take away the sum of its digits. What do you get?
  4. 4.Take 52 and take away the sum of its digits. What do you get?
  5. 5.Take 43 and take away the sum of its digits. What do you get?
  6. 6.?182 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.Take 76 and take away the sum of its digits. What do you get?
  8. 8.4?63 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.775? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.Take 99 and take away the sum of its digits. What do you get?
  11. 11.12?3 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.Take 20 and take away the sum of its digits. What do you get?
  13. 13.Take 29 and take away the sum of its digits. What do you get?
  14. 14.139? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.?087 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.?80 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.?116 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.40?6 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.?305 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.Take 39 and take away the sum of its digits. What do you get?
  21. 21.?070 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.Take 55 and take away the sum of its digits. What do you get?
  23. 23.554? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.137? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.31? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.46?6 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.?83 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.Take 30 and take away the sum of its digits. What do you get?
  29. 29.Take 12 and take away the sum of its digits. What do you get?
  30. 30.Take 94 and take away the sum of its digits. What do you get?
  31. 31.?222 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.63?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.Take 48 and take away the sum of its digits. What do you get?
  34. 34.Take 42 and take away the sum of its digits. What do you get?
  35. 35.510? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.369? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.29?6 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.?682 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.7?10 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.Take 34 and take away the sum of its digits. What do you get?

Answer key

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

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