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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 773 · 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. 1.21? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  2. 2.508? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.?57 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.3?98 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.Take 78 and take away the sum of its digits. What do you get?
  6. 6.Take 47 and take away the sum of its digits. What do you get?
  7. 7.7?30 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. 9.10?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.Take 33 and take away the sum of its digits. What do you get?
  11. 11.Take 91 and take away the sum of its digits. What do you get?
  12. 12.3?60 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.Take 74 and take away the sum of its digits. What do you get?
  14. 14.?410 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.1?42 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.64?4 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. 18.32? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.?650 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.?086 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.Take 48 and take away the sum of its digits. What do you get?
  22. 22.?085 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.Take 57 and take away the sum of its digits. What do you get?
  24. 24.78?4 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.Take 99 and take away the sum of its digits. What do you get?
  26. 26.Take 46 and take away the sum of its digits. What do you get?
  27. 27.Take 67 and take away the sum of its digits. What do you get?
  28. 28.869? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.Take 11 and take away the sum of its digits. What do you get?
  30. 30.?659 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.78?9 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.?106 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.Take 75 and take away the sum of its digits. What do you get?
  34. 34.6?22 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.Take 53 and take away the sum of its digits. What do you get?
  36. 36.Take 36 and take away the sum of its digits. What do you get?
  37. 37.?706 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.Take 64 and take away the sum of its digits. What do you get?
  39. 39.Take 19 and take away the sum of its digits. What do you get?
  40. 40.Take 22 and take away the sum of its digits. What do you get?

Answer key

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

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