Explain why it makes sense to multiply when changing from a larger unit to a smaller unit

Say you have small lego bricks (lets say 2 inch in length) and large lego bricks (lets say 3 inches in length) so you want to find out how many little legos will it take to equal 4 large ones, because they are smaller you need more to create the same length as the larger one, hints multiplying.

easiest way i can think of to help you out :)

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