I am trying to calculating $\phi(150)$
Prime factorization of $150 = 2\cdot3\cdot5^2$
So i can find $$\phi(150)= 150\cdot(1-\frac{1}{2})\cdot(1-\frac{1}{3})\cdot(1-\frac{1}{5})$$
So in case say on primefactoring three 2's come up
eg: $5\cdot2\cdot2\cdot2$ I think in prime factorization even numbers of factors is grouped together So in this case it becomes $5\cdot2\cdot2$
Is this right?
When calculating $\phi(n)$, you consider each prime factor of $n$ once and only once regardless of how many times it "appears", if that's what you're asking. Of course, it must "appear" at least once (i.e. the exponent of the prime factor in the prime factorization of $n$ must be positive).
For example, $$\begin{align}\phi\left(2^{5}\cdot3^{4}\cdot5^{3}\cdot11^{2}\right) &=\left(2^{5}\cdot3^{4}\cdot5^{3}\cdot11^{2}\right)\left(1 - \frac{1}{2}\right)\left(1-\frac{1}{3}\right)\left(1-\frac{1}{5}\right)\left(1-\frac{1}{11}\right) \\ &= 9504000\end{align}$$