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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 36 · 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 48 and take away the sum of its digits. What do you get?
  2. 2.5?49 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.55?4 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.19?7 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.Take 72 and take away the sum of its digits. What do you get?
  6. 6.?976 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.Take 80 and take away the sum of its digits. What do you get?
  8. 8.42?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.50? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.15?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.?062 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.Take 77 and take away the sum of its digits. What do you get?
  13. 13.?208 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.857? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.?627 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.67?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.37?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.Take 79 and take away the sum of its digits. What do you get?
  19. 19.Take 28 and take away the sum of its digits. What do you get?
  20. 20.1?10 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.?448 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.Take 25 and take away the sum of its digits. What do you get?
  23. 23.Take 89 and take away the sum of its digits. What do you get?
  24. 24.Take 21 and take away the sum of its digits. What do you get?
  25. 25.Take 40 and take away the sum of its digits. What do you get?
  26. 26.Take 81 and take away the sum of its digits. What do you get?
  27. 27.595? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.3?56 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.611? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.Take 34 and take away the sum of its digits. What do you get?
  31. 31.?916 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.9?3 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.2?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.?557 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.Take 11 and take away the sum of its digits. What do you get?
  36. 36.?687 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.282? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.Take 99 and take away the sum of its digits. What do you get?
  39. 39.?050 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.533? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?

Answer key

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

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