How many natural numbers less than a lakh can be formed with the digits 0,6 and 9?

Answer: Option A

The digits to be used are 0,6 and 9
The required numbers are from 1 to 99999
The numbers are five digit numbers.
Therefore, every place can be filled by 0, 6 and 9 in 3 ways.

Total number of ways = 3 × 3 × 3 × 3 × 3 = 3⁵
But 00000 is also a number formed and has to be excluded.
Total number of numbers,
= 3⁵ - 1
= 243 - 1
= 242