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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 733 · 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 21 and take away the sum of its digits. What do you get?
  2. 2.51?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.6?08 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.Take 17 and take away the sum of its digits. What do you get?
  5. 5.4?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.Take 52 and take away the sum of its digits. What do you get?
  7. 7.3?46 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.Take 14 and take away the sum of its digits. What do you get?
  9. 9.4?59 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.Take 30 and take away the sum of its digits. What do you get?
  11. 11.?385 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.Take 31 and take away the sum of its digits. What do you get?
  13. 13.8?05 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.2?97 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.89?7 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.778? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.?931 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.41?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.560? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.874? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.Take 27 and take away the sum of its digits. What do you get?
  22. 22.614? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.Take 53 and take away the sum of its digits. What do you get?
  24. 24.Take 18 and take away the sum of its digits. What do you get?
  25. 25.5?24 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.3?07 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.855? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.7?83 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.856? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.55?7 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.?587 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.Take 22 and take away the sum of its digits. What do you get?
  33. 33.?366 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.Take 59 and take away the sum of its digits. What do you get?
  35. 35.17?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.?81 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.58?9 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.Take 42 and take away the sum of its digits. What do you get?
  39. 39.400? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.29? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?

Answer key

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

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