add a feature

[Aditya70111]

its not a bug its just advise that can you add a feature in which we can pay money with algebra typing :
like-->
example :
if i buy two things worth of 68 and 45.so i first add them and then pay 113 but why not i can like this 68+45 and i click on = sign then its shows 113 on top and the pay button will enable now. ( if i do not press on ' = ' then pay button is disable )
but i think there is an issue to implement it .so if yes then can you share the issue with me else you should implement it for better user experience.

[Aditya70111]

this is not a big task if focus on simple algebra and i know you guys can add feature easily