Question

How many such pairs of digits are there in the number 8314629 each of which has as many digits between them in the number as after arranging the digits in descending order?

Accepted Answer

C. Original number: 8 3 1 4 6 2 9. Descending order: 9 8 6 4 3 2 1. Checking the pairs whose gap in the original equals the gap in the sorted sequence: (9,4), (9,6), (6,4), and (4,2). There are 4 such pairs.

Pairs of Digits in Number Rearrangement

Explanation

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