Space calculator is the world's first calculator used to calculate the possible price changes of the BTC.
It can also be used for the price calculation of any other investment goods such as shares,futures,gold,etc.
Also,it is free,and so simple.
You just choose the highest point of X and the lowest point of Y, input the values of X and Y in space calculator, click the "Calculate" button, and you will get the answer.
http://imgur.com/a/RdiiTMore,see
http://www.kjjsq.com/en.html