If you used my method from here: https://steemit.com/steemiteducation/@johnwjr7/yms8k-fun-with-5-s-3 you could make it work. You just have to remember to put the decimal point in there. 15 x 6 1/2 = 15 x 6.5. 65x15=975 then 1 decimal point = 97.5 would be the answer. I don't know if it's a better idea, but it is an idea. I never thought about using my Fun With 5's Method with a decimal, but it does seem to work.