The number of natural numbers less than one million that can be formed by using the digits, 0, 2, and 3 is
728
726
730
732
The number of k digit natural numbers formed by using the digit and 3 is 23k−1
∴ Number of natural numbers less than one million formed by 0,2 and 3 is
=2+(2)(3)+(2)32+233+234+235=728