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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 656 · 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 63 and take away the sum of its digits. What do you get?
  2. 2.21?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.182? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.?242 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.Take 31 and take away the sum of its digits. What do you get?
  6. 6.?640 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.Take 82 and take away the sum of its digits. What do you get?
  8. 8.?30 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.786? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.797? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.?647 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.23?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.493? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.375? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.8?11 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.35?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.?075 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.10?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.354? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.?79 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.401? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.393? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.?038 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.123? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.Take 92 and take away the sum of its digits. What do you get?
  26. 26.5?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.8?6 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.Take 99 and take away the sum of its digits. What do you get?
  29. 29.Take 21 and take away the sum of its digits. What do you get?
  30. 30.Take 12 and take away the sum of its digits. What do you get?
  31. 31.3?27 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.Take 74 and take away the sum of its digits. What do you get?
  33. 33.482? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.2?08 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.303? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.?166 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.?098 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.47?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.28?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.Take 93 and take away the sum of its digits. What do you get?

Answer key

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

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