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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 320 · 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.?640 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  2. 2.Take 85 and take away the sum of its digits. What do you get?
  3. 3.53?6 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.68?3 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.2?75 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.6?30 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.?177 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.391? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.?611 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.4?41 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.?60 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.?458 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.Take 33 and take away the sum of its digits. What do you get?
  14. 14.Take 95 and take away the sum of its digits. What do you get?
  15. 15.235? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.Take 76 and take away the sum of its digits. What do you get?
  17. 17.?746 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.Take 18 and take away the sum of its digits. What do you get?
  19. 19.Take 82 and take away the sum of its digits. What do you get?
  20. 20.48?3 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.7?06 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.?044 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.6?29 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.Take 45 and take away the sum of its digits. What do you get?
  25. 25.?286 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.?910 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.246? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.Take 65 and take away the sum of its digits. What do you get?
  29. 29.Take 89 and take away the sum of its digits. What do you get?
  30. 30.5?4 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.3?07 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.Take 94 and take away the sum of its digits. What do you get?
  33. 33.Take 75 and take away the sum of its digits. What do you get?
  34. 34.?390 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.4?11 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.694? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.5?39 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.?330 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.301? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.6?74 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?

Answer key

  1. 8
  2. 72
  3. 4
  4. 1
  5. 4
  6. 9
  7. 3
  8. 5
  9. 1
  10. 9
  11. 3
  12. 1
  13. 27
  14. 81
  15. 8
  16. 63
  17. 1
  18. 9
  19. 72
  20. 3
  21. 5
  22. 1
  23. 1
  24. 36
  25. 2
  26. 8
  27. 6
  28. 54
  29. 72
  30. 9
  31. 8
  32. 81
  33. 63
  34. 6
  35. 3
  36. 8
  37. 1
  38. 3
  39. 5
  40. 1

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