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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 382 · 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 87 and take away the sum of its digits. What do you get?
  2. 2.34?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.?641 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.55?6 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.?12 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.7?72 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.1?44 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.Take 81 and take away the sum of its digits. What do you get?
  9. 9.?096 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.Take 12 and take away the sum of its digits. What do you get?
  11. 11.1?16 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.467? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.83? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.?700 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.?528 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.9?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.768? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.Take 82 and take away the sum of its digits. What do you get?
  19. 19.308? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.?688 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.Take 97 and take away the sum of its digits. What do you get?
  22. 22.?922 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.Take 80 and take away the sum of its digits. What do you get?
  24. 24.47?4 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.17?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.?287 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.36?9 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.Take 22 and take away the sum of its digits. What do you get?
  29. 29.Take 38 and take away the sum of its digits. What do you get?
  30. 30.100? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.809? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.?460 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.354? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.66?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.Take 41 and take away the sum of its digits. What do you get?
  36. 36.?299 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.Take 93 and take away the sum of its digits. What do you get?
  38. 38.Take 13 and take away the sum of its digits. What do you get?
  39. 39.3?7 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.Take 34 and take away the sum of its digits. What do you get?

Answer key

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

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