Question

How many numbers between 10 and 10,000 can be formed by using the digits 1, 2, 3, 4, 5 if digits can be repeated.

Answer 1

Number of two digit numbers $=5\times 5=25$
Number of three digit numbers $=5\times 5\times 5=125$
Number of four digit numbers $=5\times 5\times 5\times 5=625$
Total $=775$