①16\2.5=16*4/(2.5*4)=64/10=6.4
②25*3.2*125
=25*(4*8/10)*125
=25*4*125*8/10
=100*1000/10
=10000
③102*35
=(100+2)*35
=35*100+35*2
=3500+70
=3570