3.12 - 4 ÷ 30.9 - 1 ÷ 2 - 0.4
3.12 - (4 ÷ 30.9) - (1 ÷ 2) - 0.4=2.090550........etc
3.12 - .12945 - .50 - .4=
3.12 - 1.02945=2.099550........etc.
