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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 910 · 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.?957 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  2. 2.8?69 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.Take 76 and take away the sum of its digits. What do you get?
  4. 4.6?88 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.?472 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.?625 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.Take 45 and take away the sum of its digits. What do you get?
  8. 8.Take 79 and take away the sum of its digits. What do you get?
  9. 9.5?42 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.39?3 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.?736 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.3?20 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.880? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.Take 67 and take away the sum of its digits. What do you get?
  15. 15.?223 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.203? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.?430 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.70? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.3?76 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.?962 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.2?55 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.708? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.Take 68 and take away the sum of its digits. What do you get?
  24. 24.3?93 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.Take 88 and take away the sum of its digits. What do you get?
  26. 26.?457 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.?075 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.2?75 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.?580 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.58?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.14?6 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.1?54 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.258? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.Take 64 and take away the sum of its digits. What do you get?
  35. 35.?602 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.1?14 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.43?3 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.Take 25 and take away the sum of its digits. What do you get?
  39. 39.Take 66 and take away the sum of its digits. What do you get?
  40. 40.5?09 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?

Answer key

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

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