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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 433 · 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. 1.50? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  2. 2.7?9 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.?175 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.84?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.82? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.?488 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.1?31 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.641? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.381? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.Take 87 and take away the sum of its digits. What do you get?
  11. 11.Take 81 and take away the sum of its digits. What do you get?
  12. 12.Take 59 and take away the sum of its digits. What do you get?
  13. 13.50?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.Take 88 and take away the sum of its digits. What do you get?
  15. 15.2?85 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.80?3 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.147? 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.?883 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.?30 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.?134 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.65?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.Take 30 and take away the sum of its digits. What do you get?
  24. 24.87?4 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.22?6 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.2?51 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.?005 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.Take 60 and take away the sum of its digits. What do you get?
  29. 29.4?19 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.?31 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.632? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.Take 27 and take away the sum of its digits. What do you get?
  33. 33.382? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.1?97 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.Take 28 and take away the sum of its digits. What do you get?
  36. 36.1?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.8?62 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.?007 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.55?5 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. 4
  2. 2
  3. 5
  4. 1
  5. 8
  6. 7
  7. 4
  8. 7
  9. 6
  10. 72
  11. 72
  12. 45
  13. 8
  14. 72
  15. 3
  16. 7
  17. 6
  18. 27
  19. 8
  20. 6
  21. 1
  22. 2
  23. 27
  24. 8
  25. 8
  26. 1
  27. 4
  28. 54
  29. 4
  30. 5
  31. 7
  32. 18
  33. 5
  34. 1
  35. 18
  36. 8
  37. 2
  38. 2
  39. 3
  40. 63

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