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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 9 · 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.?829 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  2. 2.45?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.Take 36 and take away the sum of its digits. What do you get?
  4. 4.19?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.15?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.2?07 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.Take 31 and take away the sum of its digits. What do you get?
  8. 8.Take 41 and take away the sum of its digits. What do you get?
  9. 9.20?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.Take 54 and take away the sum of its digits. What do you get?
  11. 11.?421 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.Take 33 and take away the sum of its digits. What do you get?
  13. 13.?53 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.?472 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.Take 32 and take away the sum of its digits. What do you get?
  16. 16.?221 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.?716 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.Take 46 and take away the sum of its digits. What do you get?
  19. 19.Take 81 and take away the sum of its digits. What do you get?
  20. 20.?807 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.?51 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.Take 26 and take away the sum of its digits. What do you get?
  23. 23.Take 87 and take away the sum of its digits. What do you get?
  24. 24.591? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.5?69 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.Take 77 and take away the sum of its digits. What do you get?
  27. 27.70?7 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.437? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.505? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.?18 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.7?17 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.Take 50 and take away the sum of its digits. What do you get?
  33. 33.?632 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.?748 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.7?30 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.?259 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.11?4 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.?499 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.27?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.?652 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. 1
  3. 27
  4. 3
  5. 1
  6. 9
  7. 27
  8. 36
  9. 6
  10. 45
  11. 2
  12. 27
  13. 1
  14. 5
  15. 27
  16. 4
  17. 4
  18. 36
  19. 72
  20. 3
  21. 3
  22. 18
  23. 72
  24. 3
  25. 7
  26. 63
  27. 4
  28. 4
  29. 8
  30. 9
  31. 3
  32. 45
  33. 7
  34. 8
  35. 8
  36. 2
  37. 3
  38. 5
  39. 1
  40. 5

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