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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 321 · 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. 2.884? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.Take 80 and take away the sum of its digits. What do you get?
  4. 4.3?74 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.Take 45 and take away the sum of its digits. What do you get?
  6. 6.?923 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.?004 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.Take 24 and take away the sum of its digits. What do you get?
  9. 9.?571 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.7?01 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.?341 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.Take 87 and take away the sum of its digits. What do you get?
  13. 13.3?42 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.3?60 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.?086 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.Take 15 and take away the sum of its digits. What do you get?
  17. 17.121? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.Take 76 and take away the sum of its digits. What do you get?
  19. 19.?044 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.Take 72 and take away the sum of its digits. What do you get?
  21. 21.Take 13 and take away the sum of its digits. What do you get?
  22. 22.62? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.?420 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.672? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.5?84 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.2?54 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.?449 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.?068 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.5?08 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.?83 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.793? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.6?87 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. 34.2?25 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.Take 99 and take away the sum of its digits. What do you get?
  36. 36.602? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.2?60 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.5?60 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.Take 51 and take away the sum of its digits. What do you get?
  40. 40.?694 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. 7
  3. 72
  4. 4
  5. 36
  6. 4
  7. 5
  8. 18
  9. 5
  10. 1
  11. 1
  12. 72
  13. 9
  14. 9
  15. 4
  16. 9
  17. 5
  18. 63
  19. 1
  20. 63
  21. 9
  22. 1
  23. 3
  24. 3
  25. 1
  26. 7
  27. 1
  28. 4
  29. 5
  30. 7
  31. 8
  32. 6
  33. 36
  34. 9
  35. 81
  36. 1
  37. 1
  38. 7
  39. 45
  40. 8

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