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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 768 · 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 48 and take away the sum of its digits. What do you get?
  2. 2.Take 91 and take away the sum of its digits. What do you get?
  3. 3.Take 80 and take away the sum of its digits. What do you get?
  4. 4.?020 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.?266 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.85?4 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.30?4 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.706? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.Take 74 and take away the sum of its digits. What do you get?
  10. 10.230? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.Take 15 and take away the sum of its digits. What do you get?
  12. 12.Take 57 and take away the sum of its digits. What do you get?
  13. 13.Take 52 and take away the sum of its digits. What do you get?
  14. 14.530? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.?230 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.Take 60 and take away the sum of its digits. What do you get?
  17. 17.6?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.747? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.Take 58 and take away the sum of its digits. What do you get?
  20. 20.718? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.Take 90 and take away the sum of its digits. What do you get?
  22. 22.7?45 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.Take 88 and take away the sum of its digits. What do you get?
  24. 24.Take 64 and take away the sum of its digits. What do you get?
  25. 25.?832 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.3?61 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.28?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.28?9 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.538? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.80?7 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.?69 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.56?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.Take 22 and take away the sum of its digits. What do you get?
  34. 34.?929 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.1?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.?804 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.Take 53 and take away the sum of its digits. What do you get?
  38. 38.Take 55 and take away the sum of its digits. What do you get?
  39. 39.?76 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.?785 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?

Answer key

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

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