How many 4-digit numbers are there with no digit repeated?

Question

Philoid · Accepted Answer

Total number of digits possible at a place (except 4^th place)=10

At 4^th place, there cannot be a zero(it will become 3 digit number),

No. of digits possible at 4^th place=9.

⇒ No. of permutations=

Hence, total no. of permutations=9× 504=4536.