let's firstly conver the mixed fractions to improper fractions and then get their product.
[tex]\stackrel{mixed}{4\frac{1}{2}}\implies \cfrac{4\cdot 2+1}{2}\implies \stackrel{improper}{\cfrac{9}{2}} ~\hfill \stackrel{mixed}{2\frac{1}{2}}\implies \cfrac{2\cdot 2+1}{2}\implies \stackrel{improper}{\cfrac{5}{2}} \\\\[-0.35em] ~\dotfill\\\\ \cfrac{9}{2}\cdot \cfrac{5}{2}\cdot 6\implies \cfrac{270}{2}\implies 135[/tex]
hmmm I take it that one can write that mixed as [tex]135\frac{0}{2}[/tex].
is valid, not that it makes any sense.