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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 57 · 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 69 and take away the sum of its digits. What do you get?
  2. 2.21? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.10? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.Take 17 and take away the sum of its digits. What do you get?
  5. 5.76?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.6?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.?435 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.81?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.33?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.Take 11 and take away the sum of its digits. What do you get?
  11. 11.209? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.?946 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.893? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.?033 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.?944 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.?490 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.8?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.Take 43 and take away the sum of its digits. What do you get?
  19. 19.Take 85 and take away the sum of its digits. What do you get?
  20. 20.?462 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.Take 39 and take away the sum of its digits. What do you get?
  22. 22.Take 68 and take away the sum of its digits. What do you get?
  23. 23.317? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.83?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.2?83 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.Take 23 and take away the sum of its digits. What do you get?
  27. 27.399? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.?136 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.Take 36 and take away the sum of its digits. What do you get?
  30. 30.Take 50 and take away the sum of its digits. What do you get?
  31. 31.6?96 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.514? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.874? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.3?05 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.82?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.7?99 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.Take 81 and take away the sum of its digits. What do you get?
  38. 38.?230 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.7?41 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.?494 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?

Answer key

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

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