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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 40 · 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 23 and take away the sum of its digits. What do you get?
  2. 2.Take 51 and take away the sum of its digits. What do you get?
  3. 3.?68 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.1?06 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.?058 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.?30 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.Take 94 and take away the sum of its digits. What do you get?
  8. 8.22?6 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.?02 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.Take 43 and take away the sum of its digits. What do you get?
  11. 11.?764 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.824? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.Take 33 and take away the sum of its digits. What do you get?
  14. 14.27?7 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.Take 37 and take away the sum of its digits. What do you get?
  16. 16.5?27 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.198? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.?37 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.?543 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.20? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.2?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.6?84 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.4?54 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.2?28 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.?62 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.23?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.?947 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.?869 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.7?47 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.Take 18 and take away the sum of its digits. What do you get?
  31. 31.4?30 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.Take 60 and take away the sum of its digits. What do you get?
  33. 33.86?9 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.Take 73 and take away the sum of its digits. What do you get?
  35. 35.5?46 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.Take 72 and take away the sum of its digits. What do you get?
  37. 37.?859 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.1?69 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.Take 21 and take away the sum of its digits. What do you get?
  40. 40.?662 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. 45
  3. 4
  4. 2
  5. 5
  6. 6
  7. 81
  8. 8
  9. 7
  10. 36
  11. 1
  12. 4
  13. 27
  14. 2
  15. 27
  16. 4
  17. 9
  18. 8
  19. 6
  20. 7
  21. 2
  22. 9
  23. 5
  24. 6
  25. 1
  26. 8
  27. 7
  28. 4
  29. 9
  30. 9
  31. 2
  32. 54
  33. 4
  34. 63
  35. 3
  36. 63
  37. 5
  38. 2
  39. 18
  40. 4

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