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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 450 · 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. 1.7?72 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  2. 2.Take 48 and take away the sum of its digits. What do you get?
  3. 3.Take 81 and take away the sum of its digits. What do you get?
  4. 4.Take 89 and take away the sum of its digits. What do you get?
  5. 5.6?09 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.280? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.?68 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.Take 19 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 11 and take away the sum of its digits. What do you get?
  11. 11.?322 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.Take 93 and take away the sum of its digits. What do you get?
  13. 13.81?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.Take 95 and take away the sum of its digits. What do you get?
  15. 15.1?49 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.?57 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.459? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.7?37 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.Take 51 and take away the sum of its digits. What do you get?
  20. 20.32?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.44?6 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.Take 82 and take away the sum of its digits. What do you get?
  23. 23.426? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.4?38 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.86?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.Take 79 and take away the sum of its digits. What do you get?
  27. 27.?994 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.635? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.Take 18 and take away the sum of its digits. What do you get?
  30. 30.?915 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.48?3 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.7?99 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.77?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.848? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.Take 17 and take away the sum of its digits. What do you get?
  36. 36.184? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.Take 21 and take away the sum of its digits. What do you get?
  38. 38.Take 63 and take away the sum of its digits. What do you get?
  39. 39.?831 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.Take 57 and take away the sum of its digits. What do you get?

Answer key

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

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