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Let A be the set of 4 - digit numbers ab...

Let A be the set of 4 - digit numbers abcd, where `a gt b gt c gt d ` , then n (A) equals :

A

126

B

84

C

210

D

None of these

Text Solution

Verified by Experts

The correct Answer is:
C
Any selection of four digits from the ten digits 0,1,2,3,. . . ,9 gives one number.
So, the required number of numbers`=^(10)C_(4)=120`
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