When do you use 'into' and when do you use 'in to' when writing?
Here's a quick way to remember it.
If you can replace in to with 'in order to' then it's in to (with a space)
If it answers a questions of where, then it's into (no space).
Easy, right? But there's more.
If the 'to' is part of the verb (like to hear), then there's a space. Also, if you can replace the in to with 'to' then there's a space.
I ran into a friend of mine. (in order to didn't work there, so it's into)
The man came in to shake my hand. (to shake is part of the verb, but you could also put the word 'order' between in and to and it makes sense).