a, 4.5^2 -81.3^2
=4.25-81.9
=100-729
=-629
b,31.65+31.35-5000
=31.(65+35)-5000
=31.100-5000
=3100-5000
=-1900
c,2^2.25.17+5.20.27+10^2.5^6
=4.25.17+5.20.27+100.15625
=100.17+100.27+100.15625
=100.(17+27+15625)
=100.15669
=1566900
d,120:{300:[150-(2.5^3-2^3.25)]}
=120:{300:[150-(2.125-8.25)
=120:{300:[150-(250-200)
=120:{300:[150-50]
=120:{300:100}
=120:3
=40