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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 650 · 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 59 and take away the sum of its digits. What do you get?
  2. 2.70? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.3?79 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.48?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.?362 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.6?00 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.1?85 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.Take 90 and take away the sum of its digits. What do you get?
  9. 9.Take 37 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.Take 22 and take away the sum of its digits. What do you get?
  12. 12.Take 27 and take away the sum of its digits. What do you get?
  13. 13.?48 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.?152 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.615? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.Take 33 and take away the sum of its digits. What do you get?
  17. 17.?741 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.3?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.?015 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.831? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.Take 86 and take away the sum of its digits. What do you get?
  22. 22.?701 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.47?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.Take 85 and take away the sum of its digits. What do you get?
  25. 25.80?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.Take 15 and take away the sum of its digits. What do you get?
  27. 27.12?9 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.?802 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.8?89 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.Take 32 and take away the sum of its digits. What do you get?
  31. 31.Take 34 and take away the sum of its digits. What do you get?
  32. 32.Take 66 and take away the sum of its digits. What do you get?
  33. 33.Take 82 and take away the sum of its digits. What do you get?
  34. 34.Take 23 and take away the sum of its digits. What do you get?
  35. 35.8?36 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.9?9 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.?456 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.Take 54 and take away the sum of its digits. What do you get?
  39. 39.?923 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.?600 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?

Answer key

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

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