20÷(2÷0.3)÷(3÷0.4)÷(4÷0.5)÷(5÷0.6)÷(6÷0.7)
=20÷2×0.3÷3×0.4÷4×0.5÷5×0.6÷6×0.7
=10×(0.3÷3)×(0.4÷4)×(0.5÷5)×(0.6×6)×0.7
=10×0.1×0.1×0.1×0.1×0.7
=0.001×0.7
=0.0007
20÷(2÷0.3)÷(3÷0.4)÷(4÷0.5)÷(5÷0.6)÷(6÷0.7)
=20÷2×0.3÷3×0.4÷4×0.5÷5×0.6÷6×0.7
=10×(0.3÷3)×(0.4÷4)×(0.5÷5)×(0.6×6)×0.7
=10×0.1×0.1×0.1×0.1×0.7
=0.001×0.7
=0.0007