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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 225 · 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 30 and take away the sum of its digits. What do you get?
  2. 2.?934 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.Take 74 and take away the sum of its digits. What do you get?
  4. 4.890? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.Take 26 and take away the sum of its digits. What do you get?
  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 92 and take away the sum of its digits. What do you get?
  8. 8.?786 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.Take 19 and take away the sum of its digits. What do you get?
  10. 10.88?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.4?50 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.?181 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.9?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.Take 38 and take away the sum of its digits. What do you get?
  15. 15.12?6 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.3?96 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.Take 55 and take away the sum of its digits. What do you get?
  18. 18.?412 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.?440 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.?143 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.Take 63 and take away the sum of its digits. What do you get?
  22. 22.?309 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.163? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.Take 62 and take away the sum of its digits. What do you get?
  25. 25.343? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.75? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.71?7 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.?96 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.?706 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.Take 28 and take away the sum of its digits. What do you get?
  31. 31.516? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.5?03 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.Take 42 and take away the sum of its digits. What do you get?
  34. 34.66?7 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.27? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.33?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.?068 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.6?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.Take 25 and take away the sum of its digits. What do you get?
  40. 40.1?58 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?

Answer key

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

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