King Size Bed Size If I Push To Twin Size Beds Together, Is It Equal To A Queen Size Or A King Size Bed?

If I push to twin size beds together, is it equal to a queen size or a king size bed? - king size bed size

I can not afford a new mattress. So I have to push two beds together to make a larger bed. If I was a mattress and bedding for a queen or king size? What would be the best option? The beds are standard size.