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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 461 · 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 29 and take away the sum of its digits. What do you get?
  2. 2.Take 21 and take away the sum of its digits. What do you get?
  3. 3.?002 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.Take 39 and take away the sum of its digits. What do you get?
  5. 5.43?3 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.Take 13 and take away the sum of its digits. What do you get?
  7. 7.?950 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.?514 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.Take 63 and take away the sum of its digits. What do you get?
  10. 10.9?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.3?82 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.?81 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.?364 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.16?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.843? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.?204 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.Take 90 and take away the sum of its digits. What do you get?
  18. 18.Take 75 and take away the sum of its digits. What do you get?
  19. 19.433? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.Take 53 and take away the sum of its digits. What do you get?
  21. 21.2?31 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.?219 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.3?24 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.Take 11 and take away the sum of its digits. What do you get?
  25. 25.8?55 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.80?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.Take 18 and take away the sum of its digits. What do you get?
  28. 28.Take 69 and take away the sum of its digits. What do you get?
  29. 29.158? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.3?11 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.?334 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.89?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.352? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.Take 88 and take away the sum of its digits. What do you get?
  35. 35.?400 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.Take 33 and take away the sum of its digits. What do you get?
  37. 37.Take 30 and take away the sum of its digits. What do you get?
  38. 38.?075 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.Take 76 and take away the sum of its digits. What do you get?
  40. 40.335? 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. 18
  3. 7
  4. 27
  5. 8
  6. 9
  7. 4
  8. 8
  9. 54
  10. 9
  11. 5
  12. 9
  13. 5
  14. 2
  15. 3
  16. 3
  17. 81
  18. 63
  19. 8
  20. 45
  21. 3
  22. 6
  23. 9
  24. 9
  25. 9
  26. 1
  27. 9
  28. 54
  29. 4
  30. 4
  31. 8
  32. 8
  33. 8
  34. 72
  35. 5
  36. 27
  37. 27
  38. 6
  39. 63
  40. 7

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