Tính giá trị các biểu thức

1, 3.25.8+ 4.6.37 + 2.38.12
2, 11+12+13+...+20
3,2.31.12+4.6.42+8.27.3
4, 11+13+15+...+25
5, 43.17+29.57+13.43+57
6, 34+35+36+...+43
7, 879.2+879.5+879.3
8, 2+14+16+...+26
9, 26+27+25+...+33
10, 78.31+78.24+78.17+22.72
11, 1+3+5+...+97+99
12, 20+21+22+...+29+30