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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 281 · 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. 1.478? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  2. 2.Take 69 and take away the sum of its digits. What do you get?
  3. 3.57?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.?890 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.2?22 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.Take 65 and take away the sum of its digits. What do you get?
  7. 7.Take 97 and take away the sum of its digits. What do you get?
  8. 8.2?61 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.Take 44 and take away the sum of its digits. What do you get?
  10. 10.Take 24 and take away the sum of its digits. What do you get?
  11. 11.1?28 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.?868 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.55?6 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.7?22 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.756? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.43? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.?070 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.?06 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.Take 88 and take away the sum of its digits. What do you get?
  20. 20.Take 78 and take away the sum of its digits. What do you get?
  21. 21.604? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.1?34 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.29?8 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. 25.20? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.?671 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.75?9 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.268? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.1?73 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.5?82 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.72?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.420? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.39?6 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.532? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.35?9 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.Take 16 and take away the sum of its digits. What do you get?
  37. 37.?374 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.600? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.Take 32 and take away the sum of its digits. What do you get?
  40. 40.?067 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?

Answer key

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

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