10 5 3 2=21

10 + 5 +  3 * 2  = 15 + 6 = 21

$${\mathtt{10}}{\mathtt{\,\small\textbf+\,}}{\mathtt{5}}{\mathtt{\,\small\textbf+\,}}{\mathtt{3}}{\mathtt{\,\times\,}}{\mathtt{2}} = {\mathtt{21}}$$