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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 313 · 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 63 and take away the sum of its digits. What do you get?
  2. 2.Take 62 and take away the sum of its digits. What do you get?
  3. 3.7?25 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.Take 61 and take away the sum of its digits. What do you get?
  5. 5.Take 57 and take away the sum of its digits. What do you get?
  6. 6.12? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.Take 21 and take away the sum of its digits. What do you get?
  8. 8.Take 48 and take away the sum of its digits. What do you get?
  9. 9.Take 58 and take away the sum of its digits. What do you get?
  10. 10.Take 45 and take away the sum of its digits. What do you get?
  11. 11.76?6 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.4?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.Take 82 and take away the sum of its digits. What do you get?
  14. 14.617? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.636? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.Take 65 and take away the sum of its digits. What do you get?
  17. 17.87?6 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.1?05 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.29?9 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.280? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.477? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.19?9 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.419? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.Take 99 and take away the sum of its digits. What do you get?
  25. 25.Take 75 and take away the sum of its digits. What do you get?
  26. 26.8?43 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.3?15 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.Take 40 and take away the sum of its digits. What do you get?
  29. 29.99? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.Take 91 and take away the sum of its digits. What do you get?
  31. 31.Take 46 and take away the sum of its digits. What do you get?
  32. 32.Take 69 and take away the sum of its digits. What do you get?
  33. 33.Take 24 and take away the sum of its digits. What do you get?
  34. 34.Take 87 and take away the sum of its digits. What do you get?
  35. 35.Take 30 and take away the sum of its digits. What do you get?
  36. 36.56?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.76?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.?845 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.7?76 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.38?7 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. 54
  3. 4
  4. 54
  5. 45
  6. 6
  7. 18
  8. 36
  9. 45
  10. 36
  11. 8
  12. 3
  13. 72
  14. 4
  15. 3
  16. 54
  17. 6
  18. 3
  19. 7
  20. 8
  21. 9
  22. 8
  23. 4
  24. 81
  25. 63
  26. 3
  27. 9
  28. 36
  29. 9
  30. 81
  31. 36
  32. 54
  33. 18
  34. 72
  35. 27
  36. 2
  37. 4
  38. 1
  39. 7
  40. 9

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