Question

From $0$ to $9$, four digited numbers can be formed such that the digits are in ascending order is?

• A. ${}^{10}{P}_4$
• B. ${}^{10}{C}_4$
• C. ${}^{10}{P}_4-$ ${}^9{P}_3$
• D. ${}^{10}{C}_4-$ ${}^9{C}_3$

Answer 1

Answer: (A)

${}^{10}{P}_4$

As it is in ascending order, and if we select any 4 random number there will be only 1 unique way of forming the 4 digit number.

For example, if we select $3,2,7,5$ we arrange it to form $2357$.

Hence, the total number of ways we can select 4 numbers is ${}^{10}{P}_4$