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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 491 · 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 27 and take away the sum of its digits. What do you get?
  2. 2.?165 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.Take 30 and take away the sum of its digits. What do you get?
  4. 4.2?79 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.5?3 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.Take 65 and take away the sum of its digits. What do you get?
  7. 7.70?4 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.6?04 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.35?9 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.38?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.482? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.813? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.5?88 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.?683 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.Take 88 and take away the sum of its digits. What do you get?
  16. 16.?467 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.Take 91 and take away the sum of its digits. What do you get?
  18. 18.366? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.625? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.6?21 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.?078 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.6?55 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.?04 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.?761 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.?316 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.Take 96 and take away the sum of its digits. What do you get?
  27. 27.Take 43 and take away the sum of its digits. What do you get?
  28. 28.57? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.Take 89 and take away the sum of its digits. What do you get?
  30. 30.20?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.Take 52 and take away the sum of its digits. What do you get?
  32. 32.67?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.10?4 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.Take 26 and take away the sum of its digits. What do you get?
  35. 35.Take 39 and take away the sum of its digits. What do you get?
  36. 36.8?53 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.?29 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.Take 22 and take away the sum of its digits. What do you get?
  39. 39.?508 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.?35 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?

Answer key

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

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