解:原式=[11.5×(25-0.25)+0.25]×4×18
=(11.5×25-11.5×0.25+0.25)×4×18
= [11.5×25-(11.5-1)×0.25]×4×18
=11.5×25×4×18-10.5×0.25×4×18
=(11.5×18)×(25×4)-(10.5×18)×(0.25×4)
=(11.5×2×9)×100-(10.5×2×9)×1
=(23×9)×100-21×9
=(23×10-23)×100-(20×9+9)
=207×100-189
= 20700-189
= 20511