Ravish writes letters to his five friends and addresses the corresponding envelopes. The number of ways can the letters be placed in the envelopes so that at least two of them are in the wrong envelopes is 

The number of ways can the letters be placed in the envelopes so that at least two of them are in the wrong envelopes is   $5!-1=120-1=119$  

 ( Total arrangements - no wrong addressed envelopes i.e all are placed in the correct addressed envelopes )