`a) 27.16+81.21+9.21.3`
`= 27.16+21(81+9.3)`
`= 27.16+21.108`
`= 27.16+21.27.4`
`= 27(16+21.4)`
`= 27.100`
`= 2700`
`b) 36.13+64.37+9.4.87+64.9.7`
`=(36.13+9.4.87)+(64.37+64.9.7)`
`=(36.13+36.87)+(64.37+64.63)`
`=36(13+87)+64.(37+63)`
`=36.100+64.100`
`=100.(36+64)`
`=100.100`
`=10000`
`c) 2.14.98+7.4.32-28.30`
`= 28.98+28.32-28.30`
`= 28(98+32-30)`
`= 28.100`
`= 2800`
`d) 123.456+456.321-256.44`
`= 456(123+321)-256.444`
`= 456.444-256.444`
`= (456-256).444`
`= 200.444`
`= 88800`
`e) (252+2.28-5.28):2`
`= (28.9+2.28-5.28):2`
`= [28(9+2-5)]:2`
`= 28.6 :2`
`= 168:2`
`= 84`