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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 166 · 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?99 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  2. 2.7?49 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.Take 18 and take away the sum of its digits. What do you get?
  4. 4.6?69 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.899? 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.?415 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.?860 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.Take 49 and take away the sum of its digits. What do you get?
  10. 10.Take 15 and take away the sum of its digits. What do you get?
  11. 11.Take 99 and take away the sum of its digits. What do you get?
  12. 12.Take 84 and take away the sum of its digits. What do you get?
  13. 13.Take 98 and take away the sum of its digits. What do you get?
  14. 14.4?80 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.36?6 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.?165 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.701? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.36? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.580? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.730? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.Take 46 and take away the sum of its digits. What do you get?
  22. 22.?094 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.2?57 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.536? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.32? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.?312 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.Take 35 and take away the sum of its digits. What do you get?
  28. 28.?308 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.64?3 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.39?4 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.Take 26 and take away the sum of its digits. What do you get?
  32. 32.Take 27 and take away the sum of its digits. What do you get?
  33. 33.451? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.Take 74 and take away the sum of its digits. What do you get?
  35. 35.12?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.Take 94 and take away the sum of its digits. What do you get?
  37. 37.?854 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.503? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.1?23 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.Take 29 and take away the sum of its digits. What do you get?

Answer key

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

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