df = pd.DataFrame({'a':[166,34,12,56],
               'b': [27.9625,24.6825,32.738,45.344]})

print df
print (df['a']*df['b'])
print (df['a']*df['b']).round(2)

a        b
0  166  27.9625
1   34  24.6825
2   12  32.7380
3   56  45.3440
0    4641.775
1     839.205
2     392.856
3    2539.264
dtype: float64
0    4641.77
1     839.20
2     392.86
3    2539.26
dtype: float64