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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 761 · 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.?532 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  2. 2.70?9 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.Take 72 and take away the sum of its digits. What do you get?
  4. 4.32?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.25?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.Take 20 and take away the sum of its digits. What do you get?
  7. 7.Take 82 and take away the sum of its digits. What do you get?
  8. 8.832? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.?095 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.?053 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.1?95 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.Take 18 and take away the sum of its digits. What do you get?
  13. 13.?793 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.Take 31 and take away the sum of its digits. What do you get?
  15. 15.2?32 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.Take 32 and take away the sum of its digits. What do you get?
  17. 17.?20 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.220? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.47? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.Take 30 and take away the sum of its digits. What do you get?
  21. 21.?836 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.?884 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.Take 40 and take away the sum of its digits. What do you get?
  24. 24.Take 15 and take away the sum of its digits. What do you get?
  25. 25.577? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.30?3 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.Take 59 and take away the sum of its digits. What do you get?
  28. 28.?545 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.58?4 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.155? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.85?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.Take 62 and take away the sum of its digits. What do you get?
  33. 33.?606 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.Take 43 and take away the sum of its digits. What do you get?
  35. 35.?730 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.?268 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.2?29 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.3?67 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.530? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.5?31 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?

Answer key

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

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