10000+9999+9999x9999=10000+9999x(9999+1)=10000+9999x10000=10000+99990000=100000000
19999+9999*9999
=19999+9999*(10000-1)
=10000+9999+99990000-9999
=10000+99990000
=100000000
10000+1*9999+9999*9999=10000+9999*(1+9999)=10000+9999*10000=10000+99990000=100000000