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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 875 · 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?05 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  2. 2.Take 79 and take away the sum of its digits. What do you get?
  3. 3.130? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.15?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.786? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.?165 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.562? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.Take 92 and take away the sum of its digits. What do you get?
  9. 9.Take 47 and take away the sum of its digits. What do you get?
  10. 10.5?04 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.Take 53 and take away the sum of its digits. What do you get?
  12. 12.40? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.?417 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.?950 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.68?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.2?46 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.Take 65 and take away the sum of its digits. What do you get?
  18. 18.6?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.?799 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.885? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.?373 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.Take 12 and take away the sum of its digits. What do you get?
  23. 23.Take 72 and take away the sum of its digits. What do you get?
  24. 24.?042 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.74?3 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.1?96 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.150? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.?67 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.1?06 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.108? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.Take 21 and take away the sum of its digits. What do you get?
  32. 32.?85 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.Take 22 and take away the sum of its digits. What do you get?
  34. 34.30?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.Take 67 and take away the sum of its digits. What do you get?
  36. 36.6?49 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.812? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.Take 58 and take away the sum of its digits. What do you get?
  39. 39.?151 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.14?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?

Answer key

  1. 3
  2. 63
  3. 5
  4. 7
  5. 6
  6. 6
  7. 5
  8. 81
  9. 36
  10. 9
  11. 45
  12. 5
  13. 6
  14. 4
  15. 8
  16. 6
  17. 54
  18. 3
  19. 2
  20. 6
  21. 5
  22. 9
  23. 63
  24. 3
  25. 4
  26. 2
  27. 3
  28. 5
  29. 2
  30. 9
  31. 18
  32. 5
  33. 18
  34. 1
  35. 54
  36. 8
  37. 7
  38. 45
  39. 2
  40. 2

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