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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 760 · 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. 1.173? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  2. 2.189? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.Take 35 and take away the sum of its digits. What do you get?
  4. 4.Take 30 and take away the sum of its digits. What do you get?
  5. 5.79?4 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.Take 29 and take away the sum of its digits. What do you get?
  7. 7.233? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.Take 19 and take away the sum of its digits. What do you get?
  9. 9.Take 27 and take away the sum of its digits. What do you get?
  10. 10.Take 95 and take away the sum of its digits. What do you get?
  11. 11.458? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.Take 87 and take away the sum of its digits. What do you get?
  13. 13.72?9 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.Take 17 and take away the sum of its digits. What do you get?
  15. 15.2?62 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.?640 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.7?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.Take 77 and take away the sum of its digits. What do you get?
  19. 19.8?98 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.224? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.Take 93 and take away the sum of its digits. What do you get?
  22. 22.5?85 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.6?78 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.368? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.?773 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.Take 69 and take away the sum of its digits. What do you get?
  27. 27.461? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.94? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.?616 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.?195 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.790? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.6?64 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.Take 53 and take away the sum of its digits. What do you get?
  34. 34.2?87 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.Take 66 and take away the sum of its digits. What do you get?
  36. 36.Take 12 and take away the sum of its digits. What do you get?
  37. 37.Take 80 and take away the sum of its digits. What do you get?
  38. 38.14?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.Take 59 and take away the sum of its digits. What do you get?
  40. 40.?465 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. 9
  3. 27
  4. 27
  5. 7
  6. 18
  7. 1
  8. 9
  9. 18
  10. 81
  11. 1
  12. 72
  13. 9
  14. 9
  15. 8
  16. 8
  17. 3
  18. 63
  19. 2
  20. 1
  21. 81
  22. 9
  23. 6
  24. 1
  25. 1
  26. 54
  27. 7
  28. 5
  29. 5
  30. 3
  31. 2
  32. 2
  33. 45
  34. 1
  35. 54
  36. 9
  37. 72
  38. 8
  39. 45
  40. 3

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