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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 8 · 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.?281 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  2. 2.?628 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.17?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.Take 26 and take away the sum of its digits. What do you get?
  5. 5.Take 48 and take away the sum of its digits. What do you get?
  6. 6.Take 74 and take away the sum of its digits. What do you get?
  7. 7.Take 81 and take away the sum of its digits. What do you get?
  8. 8.Take 62 and take away the sum of its digits. What do you get?
  9. 9.563? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.3?10 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.3?99 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.17?9 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.Take 52 and take away the sum of its digits. What do you get?
  14. 14.Take 90 and take away the sum of its digits. What do you get?
  15. 15.Take 97 and take away the sum of its digits. What do you get?
  16. 16.116? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.8?9 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.2?85 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.Take 14 and take away the sum of its digits. What do you get?
  20. 20.69?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.44?3 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.Take 24 and take away the sum of its digits. What do you get?
  23. 23.Take 53 and take away the sum of its digits. What do you get?
  24. 24.?843 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.6?46 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.?142 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.?335 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.560? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.?226 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.27?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.649? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.Take 16 and take away the sum of its digits. What do you get?
  33. 33.440? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.6?57 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.59?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.?79 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.Take 18 and take away the sum of its digits. What do you get?
  38. 38.Take 28 and take away the sum of its digits. What do you get?
  39. 39.?564 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.?39 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?

Answer key

  1. 7
  2. 2
  3. 5
  4. 18
  5. 36
  6. 63
  7. 72
  8. 54
  9. 4
  10. 5
  11. 6
  12. 1
  13. 45
  14. 81
  15. 81
  16. 1
  17. 1
  18. 3
  19. 9
  20. 7
  21. 7
  22. 18
  23. 45
  24. 3
  25. 2
  26. 2
  27. 7
  28. 7
  29. 8
  30. 1
  31. 8
  32. 9
  33. 1
  34. 9
  35. 2
  36. 2
  37. 9
  38. 18
  39. 3
  40. 6

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