Solution:
Consider the following numbers:
[tex]-3[/tex][tex]-3.12[/tex]and the mixed number:
[tex]1\frac{1}{2}=\frac{(2\text{ x 1)+1}}{2}=\frac{3}{2}\text{ =}1.5[/tex]now, applying the usual order of the real numbers, we have that:
[tex]-3,12<-3<1.5[/tex]then, the order of the given numbers from least to greatest is:
[tex]-3.12[/tex][tex]-3[/tex][tex]1\frac{1}{2}[/tex]