Код простейшего калькулятора на qbasic:
Declare sub summa
Declare sub raznost
Declare sub proizvedenie
Declare sub chastnoe
Call summa
Call raznost
Call proizvedenie
Call chastnoe
Sub summa
Input "", a
Print "+"
Input "", b
Print "="
Print a+b
End sub
Sub raznost
Input "", c
Print "-"
Input "", d
Print "="
Print c-d
End sub
Sub proizvedenie
Input "", e
Print "*"
Input "", f
Print "="
Print e*f
End sub
Sub chastnoe
Input "", g
Print "/"
Input "", h
Print "="
Print g/h
End sub