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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 652 · 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.Take 88 and take away the sum of its digits. What do you get?
  2. 2.Take 82 and take away the sum of its digits. What do you get?
  3. 3.Take 17 and take away the sum of its digits. What do you get?
  4. 4.8?4 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.?398 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.Take 36 and take away the sum of its digits. What do you get?
  7. 7.1?86 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.Take 54 and take away the sum of its digits. What do you get?
  9. 9.Take 73 and take away the sum of its digits. What do you get?
  10. 10.1?59 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.Take 15 and take away the sum of its digits. What do you get?
  12. 12.15?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.?223 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.50?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.?935 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.708? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.Take 81 and take away the sum of its digits. What do you get?
  18. 18.848? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.Take 59 and take away the sum of its digits. What do you get?
  20. 20.Take 52 and take away the sum of its digits. What do you get?
  21. 21.Take 27 and take away the sum of its digits. What do you get?
  22. 22.Take 65 and take away the sum of its digits. What do you get?
  23. 23.Take 76 and take away the sum of its digits. What do you get?
  24. 24.7?70 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.88?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.?906 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.Take 28 and take away the sum of its digits. What do you get?
  28. 28.57?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.Take 53 and take away the sum of its digits. What do you get?
  30. 30.Take 62 and take away the sum of its digits. What do you get?
  31. 31.Take 83 and take away the sum of its digits. What do you get?
  32. 32.Take 35 and take away the sum of its digits. What do you get?
  33. 33.?041 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.2?02 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.81?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.80?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.Take 14 and take away the sum of its digits. What do you get?
  38. 38.Take 78 and take away the sum of its digits. What do you get?
  39. 39.56?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.Take 30 and take away the sum of its digits. What do you get?

Answer key

  1. 72
  2. 72
  3. 9
  4. 6
  5. 7
  6. 27
  7. 3
  8. 45
  9. 63
  10. 3
  11. 9
  12. 2
  13. 2
  14. 4
  15. 1
  16. 3
  17. 72
  18. 7
  19. 45
  20. 45
  21. 18
  22. 54
  23. 63
  24. 4
  25. 1
  26. 3
  27. 18
  28. 5
  29. 45
  30. 54
  31. 72
  32. 27
  33. 4
  34. 5
  35. 9
  36. 1
  37. 9
  38. 63
  39. 7
  40. 27

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