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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 513 · 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 26 and take away the sum of its digits. What do you get?
  2. 2.50?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.Take 44 and take away the sum of its digits. What do you get?
  4. 4.Take 15 and take away the sum of its digits. What do you get?
  5. 5.520? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.Take 54 and take away the sum of its digits. What do you get?
  7. 7.?060 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.4?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.Take 71 and take away the sum of its digits. What do you get?
  10. 10.Take 84 and take away the sum of its digits. What do you get?
  11. 11.Take 36 and take away the sum of its digits. What do you get?
  12. 12.31?9 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.836? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.?066 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.?730 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.261? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.37? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.Take 30 and take away the sum of its digits. What do you get?
  19. 19.730? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.Take 68 and take away the sum of its digits. What do you get?
  21. 21.?280 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.?032 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.110? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.24?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.?997 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.Take 79 and take away the sum of its digits. What do you get?
  28. 28.Take 41 and take away the sum of its digits. What do you get?
  29. 29.?817 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.Take 60 and take away the sum of its digits. What do you get?
  31. 31.2?99 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.?401 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.Take 96 and take away the sum of its digits. What do you get?
  34. 34.7?99 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.?788 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.27?4 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.Take 24 and take away the sum of its digits. What do you get?
  38. 38.7?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.50? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.Take 13 and take away the sum of its digits. What do you get?

Answer key

  1. 18
  2. 2
  3. 36
  4. 9
  5. 2
  6. 45
  7. 3
  8. 3
  9. 63
  10. 72
  11. 27
  12. 5
  13. 1
  14. 6
  15. 8
  16. 9
  17. 8
  18. 27
  19. 8
  20. 54
  21. 8
  22. 4
  23. 7
  24. 7
  25. 2
  26. 8
  27. 63
  28. 36
  29. 2
  30. 54
  31. 7
  32. 4
  33. 81
  34. 2
  35. 4
  36. 5
  37. 18
  38. 6
  39. 4
  40. 9

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