(1)125×6×8=(125×8)×6=6000
(2)600÷25÷4=600÷(25×4)=6
(3)755-122-78=755-(122+78)=555
(4)138×25×4=138×(25×4)=13800
(5)25×32=25×4×8=800
(6)125×16=125×4×4=2000
(7)234×80×5=234×(80×5)=93600
(8)781-499=781-500+1=282
(9)12×25=12×4×25=1200
(10)4004×25=1001×4×25=100100
(11) 25×16×125=(25×4)×(4×125)=50000
(12)(125+16)×8=125×8+16×8=1128
(13)75×24=75×4×6=1800
(14)789×99=789×(100-1)=78111
(15)800÷125=6.4
(16)1736+403=1730+400+9=2139
(17)9999+999+99+9=10000+1000+100+10-4=11106
(18)158+262+138=420+138=558
(19)375+219+381+225=(375+225)+(219+381)=1200
(20)5001-247-1021-232=5001-1021-247-232=3501
(20)(181+2564)+2719=(181+2719)+2564=5464
(21)378+44+114+242+222=(378+222)+(44+114+242)=1000
(22)276+228+353+219=1076
(23)(375+1034)+(966+125)=(375+125)+(1034+966)=2500
(24)(2130+783+270)+1017=(2130+270)+(783+1017)=2400+1800=4200
(25)899+344=1243