Compare a cell whit itself (conditional formating)

Hello,
i want to know is that possible to compare a value of a cell with itself.
for example i enter "10" in cell B2
tomorrow i want to change it to "15" and i want to know is there any way that this cell goes red because 15 is bigger than 10
and it goes green if i enter any value less than 10

thanks for your useful responds.