1.5×0.99{#blank#}1{#/blank#}1.5           1.5×1.01{#blank#}2{#/blank#}1.5

3.87×1{#blank#}3{#/blank#}3.87           1.5×0.89{#blank#}4{#/blank#}1.5+0.89

70000000000{#blank#}1{#/blank#}71亿             8平方千米{#blank#}2{#/blank#}8000000平方米

10000001{#blank#}3{#/blank#}9999999              501×30{#blank#}4{#/blank#}5010×4

  × {#blank#}1{#/blank#}               {#blank#}2{#/blank#} ÷

÷0.1{#blank#}3{#/blank#} ÷10          × × {#blank#}4{#/blank#}