69×44简便计算法:69x44=(70-1)x44=70x44-1x44=3040-44=29961200-624-76简便计算法1200-624-76=1200-(624+76)=1200-700=500
69x44=(70-1)x44=3080-44=30361200-624-76=1200-(624+76)=1200-700=500
1200—624—76=500