499-99=400

It is my number 400 today.

I've had a very, very busy day at work with a meeting after school and have had little time to look for or think of a 400 blip.

I thought of a house number but our town doesn't have very long streets - although a couple my have had a number 400. I just didn't have the time to drive along them

Then I spotted this number plate. Thought we could do some maths.

So here we are 499 - 99 = 400