The number of 4 digited numbers that can be formed using the digits 2, 4, 5, 7,8 when repetition is not allowed
Open in App
Solution
4 digits __ __ __ __ Now the first digit can be filled by any of the 5 numbers. Therefore there are 5 possibilities The second digit will have only 4 possibilities as one of the numbers gets used up by the 1st digit. Similarly the 3rd and 4th digits will have 3 and 2 possibilities respectively. Therefore no.of 4 digit numbers that can be formed are 5 x 4 x 3x 2 = 120