Normally when we use ERP system we do not need calculator for normal calculations. But we have seen many use cases when we need calculator for exceptional calculations. Like when any sales person is woking on any lead or prospect in multi currency he will need to convert some amount to the clien currency. There can be many other usecases.
Now a days we are habited to use calculator for silly calculatins also like we know 25*5= 125 but still we will go for calculator instead of using brain. So to avoid changing screen time and improve your responce time to cline tyou can use this module.