20000÷12.5÷25÷0.8÷4
=20000÷12.5÷0.8÷25÷4
=20000÷(12.5×0.8)÷(25×4)
=20000÷10÷100
=20
20000÷12.5÷25÷0.8÷4
=20000÷(12.5*0.8*25*4)
=20000÷(10*100)
=20000÷1000
=20
12.5*0.8=10
25*4=100
20000÷12.5÷25÷0.8÷4=20000÷(12.5*25*0.8*4)=20000÷10÷100=20
20000÷12.5÷25÷0.8÷4
1600÷25÷0.8÷4
64÷0.8÷4
80÷4
=20
20000÷(12.5*0.8)÷(25*4)