5×6×7×8×9分之5×6×7×8×9-1×2×3×4×5
问题描述：
5×6×7×8×9分之5×6×7×8×9-1×2×3×4×5
答
(5x6x7x8x9-1x2x3x4x5)/(5x6x7x8x9)
=1-1x2x3x4x5/5x6x7x8x9
=1-4/7x8x9
=1-1/126
=125/126