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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 723 · 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. 1.27? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  2. 2.Take 80 and take away the sum of its digits. What do you get?
  3. 3.4?64 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.Take 56 and take away the sum of its digits. What do you get?
  5. 5.49? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.7?4 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.Take 14 and take away the sum of its digits. What do you get?
  8. 8.Take 99 and take away the sum of its digits. What do you get?
  9. 9.?550 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.Take 88 and take away the sum of its digits. What do you get?
  11. 11.Take 55 and take away the sum of its digits. What do you get?
  12. 12.?029 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.185? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.Take 52 and take away the sum of its digits. What do you get?
  15. 15.666? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.812? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.?574 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.4?3 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.37?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.Take 89 and take away the sum of its digits. What do you get?
  21. 21.Take 23 and take away the sum of its digits. What do you get?
  22. 22.Take 27 and take away the sum of its digits. What do you get?
  23. 23.?40 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.25?6 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.117? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.57?9 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.Take 13 and take away the sum of its digits. What do you get?
  28. 28.Take 46 and take away the sum of its digits. What do you get?
  29. 29.?019 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.Take 69 and take away the sum of its digits. What do you get?
  31. 31.?242 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.549? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.36?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.?724 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.763? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.11? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.682? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.?582 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.Take 26 and take away the sum of its digits. What do you get?
  40. 40.Take 94 and take away the sum of its digits. What do you get?

Answer key

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

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