×2.1= 12÷ = × = ×15= 1÷4× =
0.15× = 1÷ = 0÷ = 24× = ÷ × ÷ =
①1204+879+121
②74×60%+×25+0.6
③1.2÷×(0.6﹣)
④×[﹣(+)]