In the question it is not possible to be divisible. If there is odd number will be multiplied by 2 and it will become even I.e divisible to 2.But after that the same number will subtract it thus making it odd I.e not divisible to 2. E.g - 1*2=2-1=1 which is not divisible .(1 is a natural number).The one number in the example is not divisible to2 so the statement becomes false.