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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 720 · 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 66 and take away the sum of its digits. What do you get?
  2. 2.?755 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.Take 29 and take away the sum of its digits. What do you get?
  4. 4.Take 85 and take away the sum of its digits. What do you get?
  5. 5.?146 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.Take 99 and take away the sum of its digits. What do you get?
  7. 7.7?9 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.475? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.Take 14 and take away the sum of its digits. What do you get?
  10. 10.?715 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.Take 58 and take away the sum of its digits. What do you get?
  12. 12.?115 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.?965 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.Take 39 and take away the sum of its digits. What do you get?
  15. 15.67?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.244? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.619? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.Take 21 and take away the sum of its digits. What do you get?
  19. 19.Take 43 and take away the sum of its digits. What do you get?
  20. 20.140? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.71?9 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.50?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.16?9 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.Take 27 and take away the sum of its digits. What do you get?
  25. 25.?485 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.2?59 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.2?01 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.352? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.3?20 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.?00 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.42?4 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.Take 28 and take away the sum of its digits. What do you get?
  33. 33.7?43 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.731? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.4?50 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.4?18 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.?605 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.37?3 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.?935 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.5?65 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?

Answer key

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

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