#DIV/0! - How do i avoid seeing this message?

Hello,

I was wondering is someone can help me please.

I have the attached spread sheet and I use it to monitor if I discount products do I see the uplift in sales.

For Example:

Product 1, I launched it on 21/12/18 and never sold any, discounted it on 26/04/18 and sold 2 in the last 2 weeks therefore averaging 1 per week.

If I average 1 per week for the remaining 31 weeks of the year I should see a big percentage uplift, but because my original sales are zero I see the #DIVO/0! message, is there anyway to trick excel so I see my percentage?

I hope this makes sense?