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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 822 · 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 36 and take away the sum of its digits. What do you get?
  2. 2.141? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.208? 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 47 and take away the sum of its digits. What do you get?
  6. 6.37?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.?138 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.2?65 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.Take 92 and take away the sum of its digits. What do you get?
  10. 10.Take 35 and take away the sum of its digits. What do you get?
  11. 11.Take 86 and take away the sum of its digits. What do you get?
  12. 12.574? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.?209 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.2?40 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.23?9 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.45?9 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.5?31 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.40?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.1?04 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.Take 64 and take away the sum of its digits. What do you get?
  21. 21.?033 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.Take 17 and take away the sum of its digits. What do you get?
  23. 23.283? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.4?00 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.?704 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.?982 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.Take 69 and take away the sum of its digits. What do you get?
  28. 28.?519 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.2?31 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.6?03 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.?883 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.Take 30 and take away the sum of its digits. What do you get?
  33. 33.Take 81 and take away the sum of its digits. What do you get?
  34. 34.8?99 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.35?4 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.83?3 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.494? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.4?67 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.Take 99 and take away the sum of its digits. What do you get?
  40. 40.Take 85 and take away the sum of its digits. What do you get?

Answer key

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

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