技巧是25x4=100,则算式可分解为25x4x(2x7)=100x14=1400
1400解析:25×8×7=25×(4×2)×7=(25×4)×(2×7)=100×14=1400
=(25x4)x2x7=100x2x7=200x7=1400
25X8X7=25X4X2X7=100X14=1400