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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 584 · 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. 1.18?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  2. 2.Take 21 and take away the sum of its digits. What do you get?
  3. 3.Take 79 and take away the sum of its digits. What do you get?
  4. 4.2?65 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.?340 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.Take 86 and take away the sum of its digits. What do you get?
  7. 7.Take 26 and take away the sum of its digits. What do you get?
  8. 8.5?07 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.Take 66 and take away the sum of its digits. What do you get?
  10. 10.?61 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.?376 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.8?73 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.Take 14 and take away the sum of its digits. What do you get?
  14. 14.1?73 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.3?47 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.?980 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.Take 73 and take away the sum of its digits. What do you get?
  18. 18.Take 33 and take away the sum of its digits. What do you get?
  19. 19.?498 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.87? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.?676 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.Take 49 and take away the sum of its digits. What do you get?
  23. 23.Take 32 and take away the sum of its digits. What do you get?
  24. 24.Take 23 and take away the sum of its digits. What do you get?
  25. 25.702? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.7?00 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.26?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.375? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.3?60 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.314? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.Take 12 and take away the sum of its digits. What do you get?
  32. 32.70?7 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.Take 20 and take away the sum of its digits. What do you get?
  34. 34.3?65 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.Take 15 and take away the sum of its digits. What do you get?
  36. 36.196? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.Take 89 and take away the sum of its digits. What do you get?
  38. 38.?294 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.22?4 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.72?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?

Answer key

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

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