(253+255+257+256+254)÷257
=(257-4+257-2+257+257-1+257-3)÷257
=(257×5-10)÷257
=5-10/257
=1275/257
(253十255十257十256十254)÷257=?简便运算
(253+255+257+256+254)÷257
=(257-4+257-2+257+257-1+257-3)÷257
=(257×5-10)÷257
=5-10/257
=1275/257