f:R→R is given byf(x)=[x] It is seen that f(1.2)=[1.2]=1,f(1.9)=[1.9]=1∴f(1.2)=f(1.9), but 1.2=1.9∴f is not one-one.Now, consider 0.7∈R.It is known that f(x)=[x] is always an integer. Thus, there does not exist any element x ∈R such that f(x)=0.7∴f is not onto.Hence, the greatest integer function is neither one-one nor onto.