How many 5 digit numbers can be formed by the digits 1 2 3 4 5?

Answer 1

Let the 5 digits nos be abcdef

Without Repetition ,

a can take values from (1-5) -5

b can take only 4 values since no repetition

c can take only 3 values

d can take only 2 values

e can take only 1 values

Total = 5*4*3*2*1=120

With Repetittion

a can take values from (1-5) -5

b can take 5 values since no repetition

c can take 5 values

d can take 5 values

e can take 5 values

Total = 5*5*5*5*5=3125