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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 190 · 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.?805 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  2. 2.Take 63 and take away the sum of its digits. What do you get?
  3. 3.Take 11 and take away the sum of its digits. What do you get?
  4. 4.Take 20 and take away the sum of its digits. What do you get?
  5. 5.Take 21 and take away the sum of its digits. What do you get?
  6. 6.Take 27 and take away the sum of its digits. What do you get?
  7. 7.32?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.Take 18 and take away the sum of its digits. What do you get?
  9. 9.83?7 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.82?7 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.Take 91 and take away the sum of its digits. What do you get?
  12. 12.Take 25 and take away the sum of its digits. What do you get?
  13. 13.302? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.Take 31 and take away the sum of its digits. What do you get?
  15. 15.69?9 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.701? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.Take 35 and take away the sum of its digits. What do you get?
  18. 18.25?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.4?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.66? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.5?82 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.3?87 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.?320 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.?638 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.13?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.?937 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.639? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.?087 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.2?32 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.Take 89 and take away the sum of its digits. What do you get?
  31. 31.47? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.Take 86 and take away the sum of its digits. What do you get?
  33. 33.65?3 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.?626 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.2?06 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.Take 52 and take away the sum of its digits. What do you get?
  37. 37.80?4 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.?047 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.?455 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.?580 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?

Answer key

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

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