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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 811 · 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.?09 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  2. 2.352? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.Take 42 and take away the sum of its digits. What do you get?
  4. 4.?908 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.?930 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.?805 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.294? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.?988 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.Take 34 and take away the sum of its digits. What do you get?
  10. 10.Take 18 and take away the sum of its digits. What do you get?
  11. 11.?272 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.795? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.?028 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.?835 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.Take 67 and take away the sum of its digits. What do you get?
  16. 16.Take 54 and take away the sum of its digits. What do you get?
  17. 17.Take 78 and take away the sum of its digits. What do you get?
  18. 18.Take 69 and take away the sum of its digits. What do you get?
  19. 19.Take 20 and take away the sum of its digits. What do you get?
  20. 20.?177 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.78?6 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.3?54 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.9?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.Take 32 and take away the sum of its digits. What do you get?
  25. 25.Take 62 and take away the sum of its digits. What do you get?
  26. 26.Take 27 and take away the sum of its digits. What do you get?
  27. 27.Take 12 and take away the sum of its digits. What do you get?
  28. 28.Take 73 and take away the sum of its digits. What do you get?
  29. 29.21? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.8?89 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.?456 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.Take 41 and take away the sum of its digits. What do you get?
  33. 33.874? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.1?18 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.26?7 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.82?3 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.Take 50 and take away the sum of its digits. What do you get?
  38. 38.?390 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.?38 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.697? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?

Answer key

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

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