We have to find the possible number of three-digit numbers that are formed with the numbers 0, 1, 3, 5, 7 when repetition of digits is allowed.

We will use the concept of multiplication because there are four sub jobs dependent on each other and are performed one after the other.

There are four choices for hundred’s position because there is zero also which cannot be used in hundred’s place because then our number will become a two digit number instead of a three digit number, there are five choices for the ten’s place because there are a total of five numbers, hundred's placed in which zero was not included but in ten’s place zero is included and in one’s place there are also five choices because repetition is allowed.

The number of ways in which we can form three digit numbers when repetition of digits is allowed along with given numbers 4 × 5 × 5 = 100