9999乘以9999+19999用简便算法怎么计算?

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9999乘以9999+19999用简便算法怎么计算?

9999乘以9999+19999用简便算法怎么计算?
9999乘以9999+19999用简便算法怎么计算?

9999乘以9999+19999用简便算法怎么计算?
=9999²+19998+1
=9999²+2*9999*1+1
=(9999+1)²
=10000²
=100000000

=9999?10000-1)+19999=99990000-9999+19999=100000000

9999×9999+19999
=9999×(10000-1)+10000+9999×1
=9999×(10000-1+1)+10000
=9999×10000+10000×1
=(9999+1)×10000
=10000×10000
=100000000

9999*9999+19999
=(10000-1)^2+20000-1
=10000^2-20000+1+20000-1
=100000000

(10000-1)^2+20000-1
=100000000+1-20000+20000-1
=100000000

9999x(10000+20000)-9999x(1+1)
就可以了