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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 16 · 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. 1.122? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  2. 2.35?7 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.Take 31 and take away the sum of its digits. What do you get?
  4. 4.?493 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.Take 66 and take away the sum of its digits. What do you get?
  6. 6.Take 24 and take away the sum of its digits. What do you get?
  7. 7.?790 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.4?86 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.Take 95 and take away the sum of its digits. What do you get?
  10. 10.5?14 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.699? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.216? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.?869 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.Take 49 and take away the sum of its digits. What do you get?
  15. 15.51?6 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.683? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.882? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.400? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.Take 41 and take away the sum of its digits. What do you get?
  20. 20.?100 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.Take 17 and take away the sum of its digits. What do you get?
  22. 22.5?67 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.Take 99 and take away the sum of its digits. What do you get?
  24. 24.Take 65 and take away the sum of its digits. What do you get?
  25. 25.35? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.?669 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.734? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.384? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.?105 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.88?6 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.Take 40 and take away the sum of its digits. What do you get?
  32. 32.?384 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.Take 11 and take away the sum of its digits. What do you get?
  34. 34.?02 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.11? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.Take 25 and take away the sum of its digits. What do you get?
  37. 37.1?48 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.31?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.773? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.Take 23 and take away the sum of its digits. What do you get?

Answer key

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

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