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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 553 · 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. 1.50?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  2. 2.Take 73 and take away the sum of its digits. What do you get?
  3. 3.2?72 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.?445 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.?412 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.?44 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.Take 90 and take away the sum of its digits. What do you get?
  8. 8.Take 82 and take away the sum of its digits. What do you get?
  9. 9.Take 29 and take away the sum of its digits. What do you get?
  10. 10.598? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.31? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.171? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.?278 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.208? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.520? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.Take 26 and take away the sum of its digits. What do you get?
  17. 17.Take 39 and take away the sum of its digits. What do you get?
  18. 18.Take 99 and take away the sum of its digits. What do you get?
  19. 19.463? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.Take 93 and take away the sum of its digits. What do you get?
  21. 21.?287 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.697? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.?623 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.56? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.8?23 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.Take 84 and take away the sum of its digits. What do you get?
  27. 27.Take 37 and take away the sum of its digits. What do you get?
  28. 28.13?9 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.Take 86 and take away the sum of its digits. What do you get?
  30. 30.Take 60 and take away the sum of its digits. What do you get?
  31. 31.3?87 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.40?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.5?04 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.Take 97 and take away the sum of its digits. What do you get?
  35. 35.?326 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.51? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.Take 11 and take away the sum of its digits. What do you get?
  38. 38.68? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.Take 62 and take away the sum of its digits. What do you get?
  40. 40.Take 46 and take away the sum of its digits. What do you get?

Answer key

  1. 4
  2. 63
  3. 7
  4. 5
  5. 2
  6. 1
  7. 81
  8. 72
  9. 18
  10. 5
  11. 5
  12. 9
  13. 1
  14. 8
  15. 2
  16. 18
  17. 27
  18. 81
  19. 5
  20. 81
  21. 1
  22. 5
  23. 7
  24. 7
  25. 5
  26. 72
  27. 27
  28. 5
  29. 72
  30. 54
  31. 9
  32. 9
  33. 9
  34. 81
  35. 7
  36. 3
  37. 9
  38. 4
  39. 54
  40. 36

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