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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 800 · 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 24 and take away the sum of its digits. What do you get?
  2. 2.297? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.Take 56 and take away the sum of its digits. What do you get?
  4. 4.Take 82 and take away the sum of its digits. What do you get?
  5. 5.61?7 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.Take 87 and take away the sum of its digits. What do you get?
  7. 7.Take 98 and take away the sum of its digits. What do you get?
  8. 8.36?3 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.Take 26 and take away the sum of its digits. What do you get?
  10. 10.?370 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.Take 28 and take away the sum of its digits. What do you get?
  12. 12.69?4 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.Take 62 and take away the sum of its digits. What do you get?
  14. 14.Take 16 and take away the sum of its digits. What do you get?
  15. 15.?600 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.Take 32 and take away the sum of its digits. What do you get?
  17. 17.702? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.?334 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.Take 37 and take away the sum of its digits. What do you get?
  20. 20.1?71 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.Take 92 and take away the sum of its digits. What do you get?
  22. 22.Take 67 and take away the sum of its digits. What do you get?
  23. 23.Take 59 and take away the sum of its digits. What do you get?
  24. 24.58? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.535? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.278? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.Take 85 and take away the sum of its digits. What do you get?
  28. 28.Take 76 and take away the sum of its digits. What do you get?
  29. 29.32?4 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.26?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.Take 22 and take away the sum of its digits. What do you get?
  32. 32.Take 41 and take away the sum of its digits. What do you get?
  33. 33.Take 60 and take away the sum of its digits. What do you get?
  34. 34.?861 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.Take 52 and take away the sum of its digits. What do you get?
  36. 36.82?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.24?3 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.654? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.?532 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.?442 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. 9
  3. 45
  4. 72
  5. 4
  6. 72
  7. 81
  8. 6
  9. 18
  10. 8
  11. 18
  12. 8
  13. 54
  14. 9
  15. 3
  16. 27
  17. 9
  18. 8
  19. 27
  20. 9
  21. 81
  22. 54
  23. 45
  24. 5
  25. 5
  26. 1
  27. 72
  28. 63
  29. 9
  30. 8
  31. 18
  32. 36
  33. 54
  34. 3
  35. 45
  36. 8
  37. 9
  38. 3
  39. 8
  40. 8

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