a，a＞0；当a{#blank#}1{#/blank#}1时，积大于 ，当a{#blank#}2{#/blank#}1时，积小于 ，当a{#blank#}3{#/blank#}1时，积等于 。

12.3×45={#blank#}1{#/blank#}              1.23×45={#blank#}2{#/blank#}

0.123×4.5={#blank#}3{#/blank#}             12.3×0.45={#blank#}4{#/blank#}

123×0.045={#blank#}5{#/blank#}           12.3×4.5={#blank#}6{#/blank#}

12×30={#blank#}1{#/blank#}        120×30={#blank#}2{#/blank#}

1200×3={#blank#}3{#/blank#}       12×300={#blank#}4{#/blank#}

0.5÷0.9{#blank#}1{#/blank#}0.5                0.55×0.9{#blank#}2{#/blank#}0.55

36÷0.01{#blank#}3{#/blank#}3.6×100          7.3÷0.3{#blank#}4{#/blank#}73÷3

2.69×0.96{#blank#}1{#/blank#}2.69              0.04×1.07{#blank#}2{#/blank#}0.04              1.57×0.83{#blank#}3{#/blank#}1.57

14.7×0.9{#blank#}4{#/blank#}14.7×1.09      14.7×0.9{#blank#}5{#/blank#}14.7×0.09       14.7×0.9{#blank#}6{#/blank#}147×0.09