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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 912 · 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. 1.4?74 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  2. 2.1?7 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.195? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.71?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.Take 39 and take away the sum of its digits. What do you get?
  6. 6.7?41 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.Take 64 and take away the sum of its digits. What do you get?
  8. 8.Take 52 and take away the sum of its digits. What do you get?
  9. 9.59?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.3?48 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.334? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.Take 99 and take away the sum of its digits. What do you get?
  13. 13.Take 66 and take away the sum of its digits. What do you get?
  14. 14.Take 35 and take away the sum of its digits. What do you get?
  15. 15.Take 51 and take away the sum of its digits. What do you get?
  16. 16.?321 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.?670 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.?641 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.46?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.7?82 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.9?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.7?56 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.Take 11 and take away the sum of its digits. What do you get?
  24. 24.?920 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.2?69 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.43?3 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.384? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.5?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.Take 67 and take away the sum of its digits. What do you get?
  30. 30.?822 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.?860 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.3?81 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.2?36 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.78?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.64?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.878? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.Take 33 and take away the sum of its digits. What do you get?
  38. 38.Take 32 and take away the sum of its digits. What do you get?
  39. 39.Take 31 and take away the sum of its digits. What do you get?
  40. 40.?233 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. 1
  3. 3
  4. 8
  5. 27
  6. 6
  7. 54
  8. 45
  9. 3
  10. 3
  11. 8
  12. 81
  13. 54
  14. 27
  15. 45
  16. 3
  17. 5
  18. 7
  19. 3
  20. 1
  21. 9
  22. 9
  23. 9
  24. 7
  25. 1
  26. 8
  27. 3
  28. 8
  29. 54
  30. 6
  31. 4
  32. 6
  33. 7
  34. 2
  35. 8
  36. 4
  37. 27
  38. 27
  39. 27
  40. 1

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