Holding yarn double

I am starting my first sweater following a simple pattern. And i am over thinking a simple thing….

The pattern calls for DK weight yarn. The yard i want to use is 540m/100g. I plan on holding it double to get DK weight.

So… how much stupid yarn do i order?

Double = 540m/200g
270m/100g

I need 1400m . So - 1400/270 = 5.18. So i need to order 6?