How to increase the width of a TextBox without making it Multiline?

I'm new to VS and was trying to design a simple calculator on VS2013 lately.
Well my question is clear from the heading that how can I increase the width of a TextBox without changing its behavior to Multiline? 
I have used the Multiline behavior to get a bigger TextBox because Properties tab won't let me change it. I just want don't want the input and output fields(TextBox) to be multiline as user could use enter in those fields.

Suggest me something.
Thanks