I am plotting a data file using the TGraph class. The values in y-axis are very small (10^-10) and the scale of this axis that ROOT show me uses values x 10^-9, from 0.2x10^-9 up 1.4 x 10^-9, but I would like to change this scale in order to show the scale with values between 2 x10^-10 and 14x10^-10.