Maths isn't and never has been my bestsest subject.

I've recently become registered to the VAT club, on the flat rate scheme, and accordingly I have to pay 7.5% of the VAT that I collect, only for the first year I only pay 6.5 %.
The downside is that I don't claim any VAT back unless it's a large purchase.
I'm still going to be slightly 'up' at the end of the year though I estimate.
Anyway, to save me ringing the VAT office up, how the hell, and what is the formula for working out 6.5% of 15.0%. as I have to do my first return for the end of this month?

It'll be another calculation in January when the VAT goes back up to 17.5%, but they haven't yet told me what I'm going to have to pay...problee 9% I'd have thought.