Least Common Multiple (LCM) — Definition & Examples

An average box of graham crackers contains $4$ cellophane wrapped pouches. Each pouch has $9$ sheets of graham crackers. Each sheet can be divided into $4$ pieces. $\\$ An average chocolate bar can be divided into $12$ pieces. $\\$ An average bag of marshmallows has $40$ marshmallows in it. $$$$ To make s'mores you need $1$ sheet of graham cracker, $3$ pieces of chocolate, and $1$ marshmallow. You want to buy enough of each ingredient so that it all gets used and nothing is left over. How many bars of chocolate do you need to buy?