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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 694 · 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. 1.53?7 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  2. 2.Take 25 and take away the sum of its digits. What do you get?
  3. 3.5?42 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.8?72 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.2?12 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.?650 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.?929 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.741? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.Take 21 and take away the sum of its digits. What do you get?
  10. 10.Take 50 and take away the sum of its digits. What do you get?
  11. 11.3?82 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.Take 46 and take away the sum of its digits. What do you get?
  13. 13.Take 99 and take away the sum of its digits. What do you get?
  14. 14.Take 24 and take away the sum of its digits. What do you get?
  15. 15.61?4 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.Take 16 and take away the sum of its digits. What do you get?
  17. 17.2?90 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.Take 11 and take away the sum of its digits. What do you get?
  19. 19.Take 12 and take away the sum of its digits. What do you get?
  20. 20.Take 49 and take away the sum of its digits. What do you get?
  21. 21.Take 32 and take away the sum of its digits. What do you get?
  22. 22.Take 20 and take away the sum of its digits. What do you get?
  23. 23.Take 67 and take away the sum of its digits. What do you get?
  24. 24.Take 94 and take away the sum of its digits. What do you get?
  25. 25.Take 19 and take away the sum of its digits. What do you get?
  26. 26.?068 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.?64 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.?12 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.?665 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.?026 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.Take 34 and take away the sum of its digits. What do you get?
  32. 32.Take 38 and take away the sum of its digits. What do you get?
  33. 33.Take 47 and take away the sum of its digits. What do you get?
  34. 34.347? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.8?23 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.7?08 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.?18 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.23?3 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.8?98 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.310? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?

Answer key

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

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