G2.3 Six persons $A, B, C, D, E$ and $F$ are to rotate for night shifts in alphabetical order with $A$ serving on the first Sunday, $B$ on the first Monday and so on. In the fiftieth week, which day does $A$ serve on? (Represent Sunday by 0 , Monday by $1, \ldots$, Saturday by 6 in your answer.)
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50 \times 7=350=6 \times 58+2
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$B$ serves on Saturday in the fiftieth week. $A$ serves on Friday in the fiftieth week. Answer 5.