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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 212 · 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 69 and take away the sum of its digits. What do you get?
  2. 2.Take 87 and take away the sum of its digits. What do you get?
  3. 3.2?46 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.Take 14 and take away the sum of its digits. What do you get?
  5. 5.Take 79 and take away the sum of its digits. What do you get?
  6. 6.Take 42 and take away the sum of its digits. What do you get?
  7. 7.8?70 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.Take 45 and take away the sum of its digits. What do you get?
  9. 9.81?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.5?14 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.12?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.Take 17 and take away the sum of its digits. What do you get?
  13. 13.?09 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.Take 35 and take away the sum of its digits. What do you get?
  15. 15.6?95 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.371? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.?455 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.?604 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.?795 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.32? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.104? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.Take 89 and take away the sum of its digits. What do you get?
  23. 23.72?4 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.Take 57 and take away the sum of its digits. What do you get?
  25. 25.36?3 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.?771 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.Take 28 and take away the sum of its digits. What do you get?
  28. 28.Take 59 and take away the sum of its digits. What do you get?
  29. 29.Take 93 and take away the sum of its digits. What do you get?
  30. 30.?631 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.?573 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.?00 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.?373 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.287? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.2?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.?575 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.51?7 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.23?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.?026 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.44?9 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. 72
  3. 6
  4. 9
  5. 63
  6. 36
  7. 3
  8. 36
  9. 8
  10. 8
  11. 7
  12. 9
  13. 9
  14. 27
  15. 7
  16. 7
  17. 4
  18. 8
  19. 6
  20. 4
  21. 4
  22. 72
  23. 5
  24. 45
  25. 6
  26. 3
  27. 18
  28. 45
  29. 81
  30. 8
  31. 3
  32. 9
  33. 5
  34. 1
  35. 7
  36. 1
  37. 5
  38. 2
  39. 1
  40. 1

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