(CBS) — Today is the 40th anniversary of ‘Schoolhouse Rock,’ animated educational videos loved by millions today.

WBBM’s Keith Johnson spoke with the creative mind who helped make learning fun.

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Bob Dorough was an ad musician making making a living in New York when an agency challenged him to put the multiplication tables to music.

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“It took me two or three weeks to come up with ‘Three Is A Magic Number,’” said Dorough. “I wrote ‘Three is a Magic Number’ and they loved it and more or less said write more and write more.”

Dorough said his favorites are “Three is a Magic Number” and “Lolly, Lolly, Lolly Get Your Adverbs Here.”

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Dorough is humbled and blown away by a new generation of Youtube fans. Not bad for a musician who thought “Three is a Magic Number” would end up as part of an instructional workbook.