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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 790 · 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. 1.11?9 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  2. 2.?65 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.?857 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.304? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.?982 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.Take 71 and take away the sum of its digits. What do you get?
  7. 7.2?32 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.Take 39 and take away the sum of its digits. What do you get?
  9. 9.Take 77 and take away the sum of its digits. What do you get?
  10. 10.Take 19 and take away the sum of its digits. What do you get?
  11. 11.80? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.Take 90 and take away the sum of its digits. What do you get?
  13. 13.11? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.Take 33 and take away the sum of its digits. What do you get?
  15. 15.6?74 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.Take 15 and take away the sum of its digits. What do you get?
  17. 17.Take 58 and take away the sum of its digits. What do you get?
  18. 18.?394 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.Take 25 and take away the sum of its digits. What do you get?
  20. 20.1?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.Take 30 and take away the sum of its digits. What do you get?
  22. 22.?605 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.Take 49 and take away the sum of its digits. What do you get?
  24. 24.?188 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.?077 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.Take 13 and take away the sum of its digits. What do you get?
  27. 27.?274 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.4?11 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.501? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.?910 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.Take 43 and take away the sum of its digits. What do you get?
  32. 32.Take 21 and take away the sum of its digits. What do you get?
  33. 33.660? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.?986 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.Take 47 and take away the sum of its digits. What do you get?
  36. 36.1?13 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.?511 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.60?4 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.?034 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.?646 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?

Answer key

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

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