Arithmetic operators in JADE

I'm using Jade template engine with NOde.js. I have two variables:

a = 0.0378
b = 0.1545

in Jade I do:

- var result = a + b*2

and I get a very strange number when I do #{result}

0.03780.309

It seems to concatenate the numbers as strings. Could someone tell me how can I use arithmetic operators in Jade?

Thanks