Pretty sure the answer is 19.
Here are my workings :
Seriously though - you've asked the question now, we need an answer else none of us will be able to sleep. So why don't you just perform the experiment with the same lot of washing. First full, and then 2 lots of half loads with a plugin meter as suggested?
You'll need to make sure both sets of washing has the same water content, so I'd suggest putting them on a rinse wash to make it consistent. You'll also need to make sure the experiment is performed on a full moon, else you'll get gravity issues.
As an asside, I moved into a house where there is only space for one machine, and stupidly got washer as opposed to a washer/dryer combo. Really regret it. I'm now having to use a dehumifier on days wheres too damp outside to dry. Such a PITA! ... I'm hoping this machine will conk out soon
... might be waiting a while though as it's only 6 months old.
I think the dehumidifer is cheaper, but it's far less convenient as it means hanging cloths up to dry in your house, which is fine if you have space for that! Not me. It has to go in my "study/Gym"
On average, I think the dehumidifer takes about 6 hours, which at 600w is about 3.6kW, so about 40p.