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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 187 · 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.?600 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  2. 2.5?73 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.Take 30 and take away the sum of its digits. What do you get?
  4. 4.86?3 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.470? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.?130 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.Take 88 and take away the sum of its digits. What do you get?
  8. 8.Take 91 and take away the sum of its digits. What do you get?
  9. 9.?492 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.?881 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.5?57 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.Take 81 and take away the sum of its digits. What do you get?
  13. 13.Take 65 and take away the sum of its digits. What do you get?
  14. 14.80?4 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.Take 22 and take away the sum of its digits. What do you get?
  16. 16.Take 41 and take away the sum of its digits. What do you get?
  17. 17.?050 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.29?7 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.4?80 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.35?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.Take 96 and take away the sum of its digits. What do you get?
  22. 22.1?49 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.305? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.3?89 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.Take 12 and take away the sum of its digits. What do you get?
  26. 26.Take 56 and take away the sum of its digits. What do you get?
  27. 27.?93 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.?575 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.2?29 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.?785 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.Take 76 and take away the sum of its digits. What do you get?
  32. 32.50?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.3?31 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.Take 16 and take away the sum of its digits. What do you get?
  35. 35.Take 17 and take away the sum of its digits. What do you get?
  36. 36.51?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.9?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.8?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.464? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.8?77 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?

Answer key

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

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