We can do this by the tree method. What I've done here is to divide each factor by prime numbers until we have only prime numbers left. For example the second level of the tree from the top has 350 and 2. This is because 750 = 2*350. the next level has 175 and 2 because 350 = 2*175.
At the end we are left with the prime factors and find that 700 = 7*5*5*2*2