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

• Correct answer
  A

  $625$
• B

  $400$
• C

  $196$
• D

  $120$

Solution

Odd digits $=1,3,5,7,9$
Number of four digits number with all odd digits $=5 \times 5 \times 5 \times 5=625$

Hence, the correct answer is option: 'A'.