The opposite of dividing by a fraction is multiplying by the inverse of the fraction. So, to find out what fraction to divide by you need to find what number you need to multiply 2/3 by to get 4.
2/3 x 6 = 4
So if you want to divide instead of multiply, just find the inverse of the number you are multiplying by.
The inverse of 6 is 1/6. Therefore, 2/3 divided by 1/6 equals 4.
