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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 1 · 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.?672 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  2. 2.?406 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.14?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.66?4 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.3?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.Take 91 and take away the sum of its digits. What do you get?
  7. 7.Take 22 and take away the sum of its digits. What do you get?
  8. 8.?72 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.?938 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.?878 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.437? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.Take 60 and take away the sum of its digits. What do you get?
  13. 13.Take 47 and take away the sum of its digits. What do you get?
  14. 14.885? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.?776 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.Take 81 and take away the sum of its digits. What do you get?
  17. 17.2?62 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.Take 15 and take away the sum of its digits. What do you get?
  19. 19.?510 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.?430 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.?845 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.?642 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.3?16 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.5?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.8?03 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.Take 30 and take away the sum of its digits. What do you get?
  27. 27.?079 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.Take 72 and take away the sum of its digits. What do you get?
  29. 29.69?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.5?61 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.Take 79 and take away the sum of its digits. What do you get?
  32. 32.53?4 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.7?87 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.7?98 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.60?3 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.?087 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.31?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.?299 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.Take 70 and take away the sum of its digits. What do you get?
  40. 40.?476 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?

Answer key

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

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