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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 630 · 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.?311 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  2. 2.Take 28 and take away the sum of its digits. What do you get?
  3. 3.?868 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.?283 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.Take 18 and take away the sum of its digits. What do you get?
  6. 6.Take 41 and take away the sum of its digits. What do you get?
  7. 7.Take 32 and take away the sum of its digits. What do you get?
  8. 8.780? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.2?27 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.2?50 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.?411 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.?497 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.34?3 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.1?61 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.722? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.?244 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.?586 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.Take 48 and take away the sum of its digits. What do you get?
  19. 19.Take 88 and take away the sum of its digits. What do you get?
  20. 20.?033 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.Take 55 and take away the sum of its digits. What do you get?
  22. 22.Take 92 and take away the sum of its digits. What do you get?
  23. 23.?291 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.80?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.Take 81 and take away the sum of its digits. What do you get?
  26. 26.?875 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.1?99 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.76?4 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.40?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.Take 97 and take away the sum of its digits. What do you get?
  31. 31.?688 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.85?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.12?3 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.4?39 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.87?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.Take 63 and take away the sum of its digits. What do you get?
  37. 37.Take 98 and take away the sum of its digits. What do you get?
  38. 38.9?7 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.57?6 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.Take 62 and take away the sum of its digits. What do you get?

Answer key

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

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