=1.25✘21.2✘8✘3=(1.25✘8)✘21.2✘3=10✘21.2✘3=212✘3=636
1.25×21.2×24＝1.25×21.2×（8×3）＝1.25×8＋21.2×3＝10＋63.6＝73.6
