QUESTION

CSAT

Easy

Maths

Prelims 2022

What is the number of numbers of the form 0.XY0.XY, where XX and YY are distinct non-zero digits?

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Explanation

We need to form numbers of the type 0.XY0.XY, where X and Y are distinct non-zero digits. The digits X and Y must be selected from the set of digits 1 to 9.

There are 9 options for the digit X (since it can be any digit from 1 to 9). Once X is chosen, there are 8 remaining options for the digit Y (since Y must be distinct from X).

Thus, the total number of ways to arrange X and Y is: 9×8=729 \times 8 = 72

Hence, the correct answer is 7272.

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