四年级上册数学用计算器混合运算怎么算

①先算乘除、后算加减
②有括号的要先算括号里面的。
③有简便方法的要用简便方法计算；
例如：
①7×25/26
=7x(1-1/26)
=7x1-7x1/26
=7-7/26
=6又19/26
②18又9/10×1/9
=(18+9/10)x1/9
=18x1/9+9/10x1/9
=2+1/10
=2又1/10
③21又1/19×1/20
=(20+20/19)x1/20
=20x1/20+20/19x1/20
=1+1/19
=1又1/19
④(25+2又5/21)×21/26
=(26+26/21)x21/26
=26x21/26+26/21x21/26
=21+1
=22
⑤6/11×3/7+4/11×6/7
=6/11x3/7+6/11x4/7
=6/11x(3/7+4/7)
=6/11x1
=6/11