5×9和9×5都可用口诀“五九四十五”计算．

2×3 =           4×6 =          5×4 =          4 ×2 =

4×3=           3×5=           5×3=           5×6=

5×2=           4×5=           3×6=           5×5=

4×9=           2×8=           4×7=           8×3=

8×5=           7×3=           9×3=           9×5=

三五{#blank#}1{#/blank#}         二三{#blank#}2{#/blank#}         四六{#blank#}3{#/blank#}

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