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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 934 · 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. 1.17?6 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  2. 2.Take 29 and take away the sum of its digits. What do you get?
  3. 3.507? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.Take 20 and take away the sum of its digits. What do you get?
  5. 5.28?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.36?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.?728 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.Take 17 and take away the sum of its digits. What do you get?
  9. 9.?82 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.?64 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.6?76 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.Take 19 and take away the sum of its digits. What do you get?
  13. 13.Take 23 and take away the sum of its digits. What do you get?
  14. 14.5?21 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.2?29 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.?368 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.?550 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.Take 16 and take away the sum of its digits. What do you get?
  19. 19.?81 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.Take 43 and take away the sum of its digits. What do you get?
  21. 21.?107 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.Take 82 and take away the sum of its digits. What do you get?
  23. 23.Take 25 and take away the sum of its digits. What do you get?
  24. 24.14?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.53?9 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.6?39 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.Take 73 and take away the sum of its digits. What do you get?
  28. 28.Take 53 and take away the sum of its digits. What do you get?
  29. 29.8?05 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.8?37 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.?030 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.?80 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.75?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.?76 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.390? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.Take 94 and take away the sum of its digits. What do you get?
  37. 37.Take 47 and take away the sum of its digits. What do you get?
  38. 38.?808 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.7?56 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.462? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?

Answer key

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

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