987×9-3简便方法,我知道这是找规律的,但老师出在计算提上,要简便

987×9-3简便方法,我知道这是找规律的,但老师出在计算提上,要简便

987×9-3
=987×(10-1)-3
=987×10-987-3
=9870-(987+3)
=9870-1000
=8870