Exam-style question
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A system calculates a check digit as the sum of all the other digits modulo 10. What is the check digit for 4827?.
- A.0
- B.1
- C.2
- D.8
Model answer
What a good answer should say
- 1
Explanation
Why this works
The sum of the digits is 4 + 8 + 2 + 7 = 21. 21 modulo 10 is 1, so the check digit is 1.
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