The number of natural numbers less than 7000 which can be formed by using the digits 0 , 1 , 3 , 7 , 9 (repetition of digits allowed) is equal to:

Step-by-step solution

∴ Total number formed less than 7000 = 3 × 5 × 5 × 5 = 375 ∴ Total natural number formed less than 7000 = 375 - 1 = 374 (number zero has been excluded)