9999.9×9999.9+1999999.99999.9(1994个9)×9999.9(1994个9)+1999999.9(1994个9)

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9999.9×9999.9+1999999.99999.9(1994个9)×9999.9(1994个9)+1999999.9(1994个9)
9999.9×9999.9+1999999.9
9999.9(1994个9)×9999.9(1994个9)+1999999.9(1994个9)

9999.9×9999.9+1999999.99999.9(1994个9)×9999.9(1994个9)+1999999.9(1994个9)
999.99×999.99+1999.99
=(1999...99-1000...00)×999...99+1999...99
=1999...99×999...99-1000...00×999...99
+1999...99
=1999...99×(999...99+1)-1000...00×999...99
=1999...99×1000...00-1000...00×999...99
=1000...00×(1999...99-999...99)
=1000...00×1000...00
=1000.00(共1994*2=3988个零)

(10^1994-1)^2+2*10^1994-1
=10^3988-2*10^1994+1+2*10^1994-1
=10^3988

(10^1994-1)^2+2*10^1994-1
=10^3988-2*10^1994+1+2*10^1994-1
=10^3988
so easy