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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 429 · 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. 1.3?79 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  2. 2.5?56 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.Take 98 and take away the sum of its digits. What do you get?
  4. 4.Take 78 and take away the sum of its digits. What do you get?
  5. 5.Take 65 and take away the sum of its digits. What do you get?
  6. 6.7?4 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.70? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.Take 97 and take away the sum of its digits. What do you get?
  9. 9.8?54 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.Take 99 and take away the sum of its digits. What do you get?
  11. 11.?713 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.?136 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.?155 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.?26 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.?409 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.Take 49 and take away the sum of its digits. What do you get?
  17. 17.Take 48 and take away the sum of its digits. What do you get?
  18. 18.Take 11 and take away the sum of its digits. What do you get?
  19. 19.?184 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.Take 55 and take away the sum of its digits. What do you get?
  21. 21.?289 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.3?96 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.4?04 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.106? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.186? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.Take 35 and take away the sum of its digits. What do you get?
  27. 27.246? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.861? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.Take 62 and take away the sum of its digits. What do you get?
  30. 30.Take 66 and take away the sum of its digits. What do you get?
  31. 31.Take 52 and take away the sum of its digits. What do you get?
  32. 32.108? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.?526 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.621? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.Take 59 and take away the sum of its digits. What do you get?
  36. 36.6?76 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.Take 23 and take away the sum of its digits. What do you get?
  38. 38.5?4 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.2?95 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.Take 51 and take away the sum of its digits. What do you get?

Answer key

  1. 8
  2. 2
  3. 81
  4. 63
  5. 54
  6. 7
  7. 2
  8. 81
  9. 1
  10. 81
  11. 7
  12. 8
  13. 7
  14. 1
  15. 5
  16. 36
  17. 36
  18. 9
  19. 5
  20. 45
  21. 8
  22. 9
  23. 1
  24. 2
  25. 3
  26. 27
  27. 6
  28. 3
  29. 54
  30. 54
  31. 45
  32. 9
  33. 5
  34. 9
  35. 45
  36. 8
  37. 18
  38. 9
  39. 2
  40. 45

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