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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 20 · 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 42 and take away the sum of its digits. What do you get?
  2. 2.347? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.Take 45 and take away the sum of its digits. What do you get?
  4. 4.?775 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.Take 61 and take away the sum of its digits. What do you get?
  6. 6.Take 47 and take away the sum of its digits. What do you get?
  7. 7.Take 36 and take away the sum of its digits. What do you get?
  8. 8.6?56 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.Take 24 and take away the sum of its digits. What do you get?
  10. 10.1?04 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.Take 19 and take away the sum of its digits. What do you get?
  12. 12.2?95 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.?300 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.Take 81 and take away the sum of its digits. What do you get?
  15. 15.?511 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.12? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.Take 97 and take away the sum of its digits. What do you get?
  18. 18.Take 27 and take away the sum of its digits. What do you get?
  19. 19.Take 86 and take away the sum of its digits. What do you get?
  20. 20.225? 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.?066 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.?316 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. 25.55?6 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.Take 84 and take away the sum of its digits. What do you get?
  27. 27.Take 20 and take away the sum of its digits. What do you get?
  28. 28.310? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.24?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.35?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.?263 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.30?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.34?9 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.514? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.?610 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.?419 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.7?43 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.258? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.Take 41 and take away the sum of its digits. What do you get?
  40. 40.Take 18 and take away the sum of its digits. What do you get?

Answer key

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

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