Question

How many positive numbers less than 1000 can be formed? ​

Answer 1

Answer:

You have assumed that only 3-digit numbers are allowed. However, numbers like 3, 5, 35, 63, etc. are also valid. The answer is 86.

Answer 2

Answer:

so , the hundred's place can be filled by any of the digits 2, 5, 7 and so it can be done in 3 ways. ∴ the required number of 3-digit numbers=(2×4×3)=24. Hence, the total number of required type of numbers =(2+6+24)=32.