How many different 5digit codes can be formed from the 10 di

How many different 5-digit codes can be formed from the 10 digits? Assume that no digit can be used more than once.

Solution

For the i st place all the 10 digits can be used

for the 2 nd place only 9 digits can be used

for the 3 rd place only 8 digits canbe used

for the 4 th place the remaining 7 digits can be used

for the 5 th place only 6 digits can be used

hence the no of different 5 - digits codes can be formed in 10 x9 x8x7x6 ways

= 30240 codes can be formed