45×99=45×(100-1)=45×100-45×1=4500-45=4455
45×(100-1)=4500-45=4455
45*99=45*100-45=4455
45*(100-1)=45*100-45=4455
45×99=45(100-1)=45×100-45×1=4500-45=4455