There are seven greeting cards, each of a different colour and seven envelopes of the same seven colours. The number ofways in which the cards can be put in the envelopes so that exactly four of the cards go into the envelopes of the right colours is

There are seven even greeting cards each of a different colour and seven envelopes of the same seven colours. Find the number of ways in which the cards can be put in the envelopes so that exactly four of the cards go into the envelopes of the right colour.

There are greetings cards, each of a different colour and 7 envelopes of same 7 colours as that of the cards. The number of ways in which the cards can be put in envelopes, so that exactly 4 of the cards go into envelopes of respective colour is,

If the number of ways in which 7 letters can be put in 7 envelopes such that exactly four letters are in wrong envelopes is N, then

If the number of ways in which 7 letters can be put in 7 envelopes such that exactly four letters are in wrong envelopes is N, then

Find the number of ways in which 4 letters can be put in 4 addressed envelopes so that no letter goes into the envelope meant for it.

The number of ways in which four letters can be put in four addressed envelops so that no letter goes into envelope meant for it is

The number of ways in which five different letters can be put in their five addressed envelopes so that all the letters are in the wrong envelopes is