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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 118 · 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. 1.1?60 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  2. 2.5?35 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.3?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.727? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.?071 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.433? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.?572 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.Take 71 and take away the sum of its digits. What do you get?
  9. 9.115? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.Take 77 and take away the sum of its digits. What do you get?
  11. 11.1?33 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.Take 39 and take away the sum of its digits. What do you get?
  13. 13.2?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.5?45 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.7?02 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.10?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.?913 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.3?50 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.Take 20 and take away the sum of its digits. What do you get?
  20. 20.?242 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.82?7 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.87?9 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.322? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.Take 44 and take away the sum of its digits. What do you get?
  25. 25.?061 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.Take 17 and take away the sum of its digits. What do you get?
  27. 27.88?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.?908 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.Take 81 and take away the sum of its digits. What do you get?
  30. 30.19?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.?391 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.8?02 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.73? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.1?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.4?96 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.?088 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.?643 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.?232 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.4?86 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.26?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?

Answer key

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

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