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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 108 · 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.?816 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  2. 2.52?4 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.18?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.?535 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.641? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.Take 25 and take away the sum of its digits. What do you get?
  7. 7.Take 72 and take away the sum of its digits. What do you get?
  8. 8.413? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.759? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.5?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.145? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.Take 21 and take away the sum of its digits. What do you get?
  13. 13.Take 19 and take away the sum of its digits. What do you get?
  14. 14.?80 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.Take 76 and take away the sum of its digits. What do you get?
  16. 16.?422 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.505? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.321? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.Take 23 and take away the sum of its digits. What do you get?
  20. 20.20?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.72?3 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.?008 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.314? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.6?82 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.1?80 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.Take 47 and take away the sum of its digits. What do you get?
  27. 27.64?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.Take 14 and take away the sum of its digits. What do you get?
  29. 29.Take 77 and take away the sum of its digits. What do you get?
  30. 30.59?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.611? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.Take 39 and take away the sum of its digits. What do you get?
  33. 33.7?97 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.?460 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.308? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.?005 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.?382 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.Take 37 and take away the sum of its digits. What do you get?
  39. 39.8?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.122? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?

Answer key

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

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