简便计算：①999*999+1999 ②9999*9999+19999
问题描述：
简便计算：①999*999+1999 ②9999*9999+19999
答
1）999*999+1999
=1000*999-999+1999
=999000+1000
=1000000
2）9999*9999+19999
=10000*9999-9999+19999
=99990000+10000
=100000000
答
①999×999+1999
=(1000-1)^2+1999
=1000^2-2000+1+1999
=1000000
②9999×9999+19999
=(10000-1)^2+19999
=10000^2-20000+1+19999
=100000000
答
①
999*999+1999
=(1000-1)²+1999
=1000²-2000+1+1999
=1000²
=1000000
②
9999*9999+19999
=(10000-1)²+19999
=10000²-20000+1+19999
=10000²
=100000000