Console App Question

Question

I want to ignore pressing enter key while taking inpur from user.

 

i.e. user just enter a value either it is thousands( or double varible lenght digit) or hundreds program just identify,save the value in a variable and move on next line to proceed.

 

basically it is a calculator app. and i wnat to ignore pressing enter key again and agin. 

could anyone please help me doing this?