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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 565 · 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 23 and take away the sum of its digits. What do you get?
  2. 2.309? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.2?17 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.9?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.Take 41 and take away the sum of its digits. What do you get?
  6. 6.420? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.Take 87 and take away the sum of its digits. What do you get?
  8. 8.Take 60 and take away the sum of its digits. What do you get?
  9. 9.24?9 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.373? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.?472 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.87?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.4?93 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.?055 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.Take 64 and take away the sum of its digits. What do you get?
  16. 16.208? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.7?00 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.Take 36 and take away the sum of its digits. What do you get?
  19. 19.Take 42 and take away the sum of its digits. What do you get?
  20. 20.?680 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.876? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.48?6 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.83? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.447? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.?41 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.8?82 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.Take 31 and take away the sum of its digits. What do you get?
  28. 28.2?53 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.1?40 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.Take 51 and take away the sum of its digits. What do you get?
  31. 31.8?32 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.Take 34 and take away the sum of its digits. What do you get?
  33. 33.89?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.83?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.?867 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.Take 17 and take away the sum of its digits. What do you get?
  37. 37.315? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.34?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.Take 95 and take away the sum of its digits. What do you get?
  40. 40.5?30 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?

Answer key

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

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