996×25
=(1000-4)×25
=1000×25-4×25
=25000-100
=24900
（125×99+125）×16
=125×(99+1)×16
=(125×16)×100
=2000×100
=200000
36×68-68+68×25
=(36-1+25)×68
=60×68
=4080