5x5 to the fourth power is 3125.
5 to the fourth power is 625. Now multiply 5x600 and that equals 3000. Then, add 5x25 and that equals 125. Add 125 to 300 and that equals 3125.
So, 5x5 to the fourth power equals 3125. Next time think of it as 5x(5 to the fourth power).