real numbers

we know a number is divisible by 3,if that number is a multiple of 3.

so in 5n ,its for sure that 5is not divisible by 3.

So n should be a multiple of 3.

now the question says the least value of n where n is a natural number,therefore n=3

so 5n=15 and 15 is divisible by 3   (answer)