问题：7.8x4.9+2.6x79.3用简便计算.
7.8x4.9+2.6x79.3=2.6×(3×4.9+79.3)=2.6×(14.7+79.3)=2.6×94=2.6×(100-6)=260-15.6=244.4 问题：7.8x4.9+2.6x79.3用简便计算.
7.8x4.9+2.6x79.3=2.6×(3×4.9+79.3)=2.6×(14.7+79.3)=2.6×94=2.6×(100-6)=260-15.6=244.4