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NDA 2022

Exam: NDA
Year: 2022
Subject: Mathematics
Chapter: Permutation and Combination

NDA 2022 · Mathematics · Permutation and Combination

How many four-digit natural numbers are there such that all of the...

How many four-digit natural numbers are there such that all of the digits are odd?

Options

A $625$
B $400$
C $196$
D $120$

Correct answer

A. $625$

Step-by-step solution

Odd digits

=1,3,5,7,9

Number of four digits number with all odd digits

=5 \times 5 \times 5 \times 5=625

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