Bring out the importance of hierarchy of operators? 

The operators  within  C are grouped  hierarchically according to their precedence(i.e., order of evaluation). Operations with a higher precedence  are carried out before operations having a lower precedence. The natural order of evaluation can be altered, though, by the use of parantheses. Between the arithmetic operators, *,/ and % fall into =one precedence group, and + and - fall into another. The first group has a higher precedence than the second.