Solveeit Logo
Login

Question

Question: Let A be the set of 4-digit numbers a<sub>1</sub>a<sub>2</sub>a<sub>3</sub>a<sub>4</sub> where a<sub...

Let A be the set of 4-digit numbers a1a2a3a4 where a1 > a2 > a3 > a4, then n(1) is equal to

A

126

B

84

C

210

D

None of these

Answer

210

Explanation

Solution

Any selection of four digits from the ten digits 0, 1, 2, 3,..., 9 gives one such number.

So, the required number of numbers = 10C4 = 210