ShmoopTube

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Here’s a question with a beat you can shmoop to…

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Mrs. Morrison is all about technology.

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Which is why she wants to replace all the pencils in her classroom with… mechanical pencils.

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On the first day of class, she had planned to distribute the mechanical pencils to her 30 students.

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She had figured that if every student received the same number of pencils,

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there would be 5 pencils left over. Instead of handing out the pencils on the

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first day, she decided to hold off until the size of her class had stabilized.

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A few days later, when she actually distributed the pencils, there were 25 students and there

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were still 5 pencils left after the equal distribution.

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How many pencils could Mrs. Morrison have had?

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And here are the potential answers...

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OK, so this question is just asking us to plug

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in the potential answers one by one and figure out the remainders.

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We have to get a number such that the remainder is 5 after dividing by both 25 and by 30.

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So… consider A. With 125 pencils and the 25 student alternative, there would be NO

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pencils left over – so... we can reject A.

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Consider B with 130 – in this case, we’d have remainders of 5 and 10 –

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so, not 5 and 5 which is what we seek… so punt B.

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Now C: 150. Well, 25 and 30 go into 150 evenly so there’d be NO pencils left for either solution.

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Try D: 30 into 155 gives us 150 evenly with 5 leftover;

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and 25 into 155 gives us 150 evenly with 5 leftover…

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So the answer to this oddball question...

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...and this strange woman Mrs. Morrison dot com...

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...is D.

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As in, “Don’t tell Mrs. Morrison dot com about computers.”

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