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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 15 · 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 55 and take away the sum of its digits. What do you get?
  2. 2.1?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.Take 15 and take away the sum of its digits. What do you get?
  4. 4.382? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.?322 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.Take 14 and take away the sum of its digits. What do you get?
  7. 7.?620 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.8?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.Take 73 and take away the sum of its digits. What do you get?
  10. 10.1?28 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.77?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.?498 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.2?33 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.Take 81 and take away the sum of its digits. What do you get?
  15. 15.49?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.Take 65 and take away the sum of its digits. What do you get?
  17. 17.Take 99 and take away the sum of its digits. What do you get?
  18. 18.?003 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.478? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.892? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.36?7 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.752? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.?904 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.Take 91 and take away the sum of its digits. What do you get?
  25. 25.?580 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.873? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.87?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.751? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.Take 67 and take away the sum of its digits. What do you get?
  30. 30.?301 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.38?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.?737 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.Take 49 and take away the sum of its digits. What do you get?
  34. 34.?628 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.87?7 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.Take 37 and take away the sum of its digits. What do you get?
  37. 37.?750 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.Take 46 and take away the sum of its digits. What do you get?
  39. 39.315? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.Take 77 and take away the sum of its digits. What do you get?

Answer key

  1. 45
  2. 3
  3. 9
  4. 5
  5. 2
  6. 9
  7. 1
  8. 9
  9. 63
  10. 7
  11. 8
  12. 6
  13. 1
  14. 72
  15. 4
  16. 54
  17. 81
  18. 6
  19. 8
  20. 8
  21. 2
  22. 4
  23. 5
  24. 81
  25. 5
  26. 9
  27. 7
  28. 5
  29. 54
  30. 5
  31. 6
  32. 1
  33. 36
  34. 2
  35. 5
  36. 27
  37. 6
  38. 36
  39. 9
  40. 63

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