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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 539 · 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 52 and take away the sum of its digits. What do you get?
  2. 2.Take 43 and take away the sum of its digits. What do you get?
  3. 3.?340 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.Take 29 and take away the sum of its digits. What do you get?
  5. 5.29?9 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.Take 13 and take away the sum of its digits. What do you get?
  7. 7.4?77 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.Take 38 and take away the sum of its digits. What do you get?
  9. 9.Take 91 and take away the sum of its digits. What do you get?
  10. 10.?809 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.4?47 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.?304 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.Take 81 and take away the sum of its digits. What do you get?
  14. 14.5?52 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.?93 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.Take 32 and take away the sum of its digits. What do you get?
  17. 17.2?73 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.41?7 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.?870 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.778? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.631? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.?54 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.?571 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.Take 98 and take away the sum of its digits. What do you get?
  25. 25.8?82 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.2?77 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.838? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.?858 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.Take 78 and take away the sum of its digits. What do you get?
  30. 30.Take 71 and take away the sum of its digits. What do you get?
  31. 31.10?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.?838 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.Take 42 and take away the sum of its digits. What do you get?
  34. 34.Take 39 and take away the sum of its digits. What do you get?
  35. 35.Take 59 and take away the sum of its digits. What do you get?
  36. 36.?547 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. 38.407? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.58?6 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.Take 15 and take away the sum of its digits. What do you get?

Answer key

  1. 45
  2. 36
  3. 2
  4. 18
  5. 7
  6. 9
  7. 9
  8. 27
  9. 81
  10. 1
  11. 3
  12. 2
  13. 72
  14. 6
  15. 6
  16. 27
  17. 6
  18. 6
  19. 3
  20. 5
  21. 8
  22. 9
  23. 5
  24. 81
  25. 9
  26. 2
  27. 8
  28. 6
  29. 63
  30. 63
  31. 9
  32. 8
  33. 36
  34. 27
  35. 45
  36. 2
  37. 45
  38. 7
  39. 8
  40. 9

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