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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 775 · 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. 1.2?61 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  2. 2.3?70 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.Take 56 and take away the sum of its digits. What do you get?
  4. 4.Take 14 and take away the sum of its digits. What do you get?
  5. 5.?644 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.Take 75 and take away the sum of its digits. What do you get?
  7. 7.Take 61 and take away the sum of its digits. What do you get?
  8. 8.40?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.?870 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.?202 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.859? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.707? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.Take 68 and take away the sum of its digits. What do you get?
  14. 14.?310 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.1?25 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.33? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.?950 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.Take 65 and take away the sum of its digits. What do you get?
  19. 19.Take 29 and take away the sum of its digits. What do you get?
  20. 20.3?03 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.61?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.Take 45 and take away the sum of its digits. What do you get?
  23. 23.Take 57 and take away the sum of its digits. What do you get?
  24. 24.70?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.48?9 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.86? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.Take 19 and take away the sum of its digits. What do you get?
  28. 28.139? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.?82 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.66?8 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.?314 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.384? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.Take 33 and take away the sum of its digits. What do you get?
  35. 35.Take 25 and take away the sum of its digits. What do you get?
  36. 36.40?4 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.5?14 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.Take 31 and take away the sum of its digits. What do you get?
  39. 39.?34 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. 9
  2. 8
  3. 45
  4. 9
  5. 4
  6. 63
  7. 54
  8. 5
  9. 3
  10. 5
  11. 5
  12. 4
  13. 54
  14. 5
  15. 1
  16. 3
  17. 4
  18. 54
  19. 18
  20. 3
  21. 9
  22. 36
  23. 45
  24. 6
  25. 6
  26. 4
  27. 9
  28. 5
  29. 8
  30. 7
  31. 18
  32. 1
  33. 3
  34. 27
  35. 18
  36. 1
  37. 8
  38. 27
  39. 2
  40. 54

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