Factorial!

150! = 150 x 149! . The number 150 have a zero in the end. So whatever number you're gonna multiplied 150 with, it always end with zero

We observe

From $5!$ onwards, the number will always end with $0$ because it will contain a $2$ and $5$ as it's prime factors.

So basically $n!$ will always end with zero where $n\geq5$ and $n$ is a positive integer.

$150! = k\times 10$ where $k$ is a positive integer

$\Rightarrow$ last digit $= 0$