Making your mind up

Now I don't claim to be an expert in maths, I will leave that to my son the maths teacher, but try as might I cannot fathom how you can have 100% part exchange.
But since I really like bad/unusual signage, I was so glad when June spotted this some weeks ago, I knew that it had to be a blip.
If you want a serious blip, you can always check out yesterday's one.
And if you don't Mind no skirts were ripped off in the making of this blip.