简便方法的核心就是找到共同点,先算简单的。
100x98/99
=(99+1)x(99-1)/99
=(99^2-1)/99
=99^2÷99-1/99
=99-1/99
=98又98/99
100×98/99
=(100×99/99)-(100×1/99)
=100×1-(100×1/99)
=100 -(100×1/99)
≈100 - 1.01
≈98.99
100×98/99
=(99+1)X98/99
=99X98/99+1X98/99
=98+98/99
=98又98/99
100×100=0