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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 617 · 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. 1.580? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  2. 2.50?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.74?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.4?60 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.218? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.338? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.?66 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.?708 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.Take 41 and take away the sum of its digits. What do you get?
  10. 10.11?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.?086 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.Take 59 and take away the sum of its digits. What do you get?
  13. 13.Take 30 and take away the sum of its digits. What do you get?
  14. 14.483? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.530? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.7?17 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.Take 25 and take away the sum of its digits. What do you get?
  18. 18.Take 29 and take away the sum of its digits. What do you get?
  19. 19.83? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.?41 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.Take 47 and take away the sum of its digits. What do you get?
  22. 22.Take 72 and take away the sum of its digits. What do you get?
  23. 23.Take 84 and take away the sum of its digits. What do you get?
  24. 24.80?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.?496 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.415? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.695? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.?469 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.2?55 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.Take 76 and take away the sum of its digits. What do you get?
  31. 31.11?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.Take 63 and take away the sum of its digits. What do you get?
  33. 33.?304 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.?043 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.30?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.?557 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.22?6 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.2?70 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.?289 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.739? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?

Answer key

  1. 5
  2. 4
  3. 5
  4. 8
  5. 7
  6. 4
  7. 6
  8. 3
  9. 36
  10. 7
  11. 4
  12. 45
  13. 27
  14. 3
  15. 1
  16. 3
  17. 18
  18. 18
  19. 7
  20. 4
  21. 36
  22. 63
  23. 72
  24. 1
  25. 8
  26. 8
  27. 7
  28. 8
  29. 6
  30. 63
  31. 8
  32. 54
  33. 2
  34. 2
  35. 1
  36. 1
  37. 8
  38. 9
  39. 8
  40. 8

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