用简便方法计算.1.99×99+199 2.999×778+333×666

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用简便方法计算.1.99×99+199 2.999×778+333×666

用简便方法计算.1.99×99+199 2.999×778+333×666
用简便方法计算.1.99×99+199 2.999×778+333×666

用简便方法计算.1.99×99+199 2.999×778+333×666
99×99+199
=99x99+100+99x1
=99x(99+1)+100
=99x100+100x1
=100x(99+1)
999×778+333×666
=999x778+333x3x222
=999x778+999x222
=999x(778+222)
=999x1000
=999000