A Gauss brand light bulb will work for 24999 hours. If it is used for exactly 2 hours every day starting on a Monday, on what day of the week will it stop working?
(A) Thursday
(B) Friday
(C) Saturday
(D) Sunday
(E) Monday
The lightbulb is used for exactly 2 hours every day and it will work for 24999 hours.

Thus, the lightbulb will work for $24999 \div 2=12499.5$ days, which means that it will stop working on the $12500^{\text {th }}$ day.

How many weeks are there in 12500 days?

Since $12500 \div 7 \approx 1785.71$, there are between 1785 and 1786 weeks in 12500 days.

Specifically, $12500-7 \times 1785=12500-12495=5$, and so there are 1785 complete weeks and 5 additional days in 12500 days.

The lightbulb starts being used on a Monday and so the last day of 1785 complete weeks will be a Sunday.

The lightbulb will stop working 5 days past Sunday, which is a Friday.

ANSWER: (B)