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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 644 · 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 48 and take away the sum of its digits. What do you get?
  2. 2.86? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.65?4 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.Take 72 and take away the sum of its digits. What do you get?
  5. 5.7?9 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.Take 65 and take away the sum of its digits. What do you get?
  7. 7.Take 78 and take away the sum of its digits. What do you get?
  8. 8.?874 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.23?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.?750 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.518? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.Take 53 and take away the sum of its digits. What do you get?
  13. 13.Take 50 and take away the sum of its digits. What do you get?
  14. 14.13?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.689? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.25?7 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.104? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.139? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.?503 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.?51 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.2?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.?29 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.Take 55 and take away the sum of its digits. What do you get?
  24. 24.517? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.59?3 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.253? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.?736 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.65?3 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.Take 96 and take away the sum of its digits. What do you get?
  30. 30.740? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.Take 93 and take away the sum of its digits. What do you get?
  32. 32.?193 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.443? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.Take 79 and take away the sum of its digits. What do you get?
  35. 35.?62 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.1?63 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.1?14 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.80? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.6?93 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.?496 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?

Answer key

  1. 36
  2. 4
  3. 3
  4. 63
  5. 2
  6. 54
  7. 63
  8. 8
  9. 5
  10. 6
  11. 4
  12. 45
  13. 45
  14. 9
  15. 4
  16. 4
  17. 4
  18. 5
  19. 1
  20. 3
  21. 6
  22. 7
  23. 45
  24. 5
  25. 1
  26. 8
  27. 2
  28. 4
  29. 81
  30. 7
  31. 81
  32. 5
  33. 7
  34. 63
  35. 1
  36. 8
  37. 3
  38. 1
  39. 9
  40. 8

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