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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 181 · 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 76 and take away the sum of its digits. What do you get?
  2. 2.Take 92 and take away the sum of its digits. What do you get?
  3. 3.Take 96 and take away the sum of its digits. What do you get?
  4. 4.5?04 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.?716 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.860? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.441? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.Take 65 and take away the sum of its digits. What do you get?
  9. 9.?272 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.62?6 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.582? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.824? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.?944 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.Take 58 and take away the sum of its digits. What do you get?
  15. 15.?934 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.?550 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.5?07 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.?506 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.?160 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.234? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.Take 77 and take away the sum of its digits. What do you get?
  22. 22.Take 40 and take away the sum of its digits. What do you get?
  23. 23.7?53 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.Take 49 and take away the sum of its digits. What do you get?
  25. 25.509? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.?770 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.?015 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.?24 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.Take 66 and take away the sum of its digits. What do you get?
  30. 30.581? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.83?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.30?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.5?18 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.Take 59 and take away the sum of its digits. What do you get?
  35. 35.9?4 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.Take 30 and take away the sum of its digits. What do you get?
  37. 37.Take 42 and take away the sum of its digits. What do you get?
  38. 38.?744 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.624? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.8?57 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?

Answer key

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

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