,估算:48×32≈ 46×79≈ 103×21≈ 41×19≈ 72×78≈ 61×60≈ .
巧算。543+318+157188+77+512
巧算。754-344-154867-345-222
巧算。456-88-156966-435-166
巧算。732-168-232654-231-154
巧算。375-137-63582-120-82