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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 619 · 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. 1.3?51 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  2. 2.Take 88 and take away the sum of its digits. What do you get?
  3. 3.475? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.3?74 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.73?6 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.?268 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.1?46 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.?674 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.12?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.2?70 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.8?69 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.Take 74 and take away the sum of its digits. What do you get?
  13. 13.?151 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.3?49 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.Take 56 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.?447 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.6?11 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.56? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.Take 66 and take away the sum of its digits. What do you get?
  21. 21.84?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.2?9 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.4?03 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.260? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.2?46 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.Take 30 and take away the sum of its digits. What do you get?
  27. 27.?571 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.14?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.Take 38 and take away the sum of its digits. What do you get?
  30. 30.?345 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.58?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.Take 21 and take away the sum of its digits. What do you get?
  33. 33.2?88 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.?121 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.?678 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.Take 20 and take away the sum of its digits. What do you get?
  37. 37.Take 13 and take away the sum of its digits. What do you get?
  38. 38.?492 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.Take 29 and take away the sum of its digits. What do you get?
  40. 40.?077 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?

Answer key

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

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