Number Model With Unknown. A number model is a way to. Nine times eight is 72, so nine times eight, nine times eight is equal to 72.

So, we can say that a is equal to 72 and if a is equal to 72, then this. Represent unknown numbers using symbols or lettersin this lesson you will learn how to represent an unknown number in an equation by using a symbol or a lett. A number model is often used in math when showing a problem visually with pictures or physically with manipulatives.