F2 mathz easy plz help

以上的朋友沒有依題目指示來估計數字...
"Estimate the values of the following expression"

1)12+3.2+3.4+7.9+11. 3+5.5+8.1+4.5
= 12+3+3+8+11+6+8+5
= 56

2)0.556 x 18.21
= 0.5 x 18
= 9

3) (348x3.09)/20.8
= (350x3)/21
= 1050/21
= 50

4)7.91+6.85+7.13+9.01+ 8.89
= 8+7+7+9+9
= 40

5) 12.1 - 7.9-1.89+4.08+8 .8
= 12 - 8 - 2+4+9
= 15

6) 8.94-29.91+139.02+80 .25-21.89-12.73
= 9 - 30 + 139+80+22+13
= 189

1)55.9

2)10.12476

3)51.698076

4)39.79

5)15.19

6)163.68