口算.6×7= 9×9= 3×6= 2×6=8×3+4= 36+4= 8×7= 2×2=9+57= 3×4+9= 5×6= 18+60=9×3= 5×5= 38﹣18+25= 41﹣2=6×9= 8×5= 7×2= 7×5﹣3=
简便运算. 1.25×0.25×0.05×64= ;0.525÷13.125÷4×85.2= ;+++= ;++++= .
36×72+36×27+36125×32×254.64﹣(0.64+3.62) 21÷9+22÷9+23÷9+24÷9199999.9+19999.8+1999.9+199.8+19.9+0.7.
321×3.3﹣123÷= 326 .
(7.5+7.5+7.5+7.5)×125×4.
1999+999×999.