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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 422 · 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 89 and take away the sum of its digits. What do you get?
  2. 2.?400 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.6?43 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.Take 46 and take away the sum of its digits. What do you get?
  5. 5.Take 30 and take away the sum of its digits. What do you get?
  6. 6.622? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.5?73 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.8?40 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.4?26 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.Take 45 and take away the sum of its digits. What do you get?
  11. 11.?232 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.Take 65 and take away the sum of its digits. What do you get?
  13. 13.Take 53 and take away the sum of its digits. What do you get?
  14. 14.793? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.Take 74 and take away the sum of its digits. What do you get?
  16. 16.674? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.53?7 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.21? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.?37 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.4?51 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.Take 91 and take away the sum of its digits. What do you get?
  22. 22.Take 27 and take away the sum of its digits. What do you get?
  23. 23.62?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.Take 52 and take away the sum of its digits. What do you get?
  25. 25.309? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.588? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.?138 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.86?3 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.1?19 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.Take 84 and take away the sum of its digits. What do you get?
  31. 31.?448 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.2?68 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.5?75 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.?343 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.36? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.Take 15 and take away the sum of its digits. What do you get?
  37. 37.610? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.594? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.Take 95 and take away the sum of its digits. What do you get?
  40. 40.2?79 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?

Answer key

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

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