reason *****
reason out
conclude ***

She looked surprised that I had to reason it out.

Now it was telling him things that he didn't understand, couldn't reason out.

"I can never reason out what hour it is in the Waste."

She pulled herself together and tried to reason it out.

I tried to reason out what had happened, but could not fit any of the known factors together, and finally gave the matter up.

He reasons out what she must have done and follows her.

He went back to the beginning to try to reason it out.

"But no matter how you reason it out, that would still only make her your second wife."

It's not the sort of thing you can reason out.

She shook her head and tried to reason out what had happened.