10^4 means to multiply it by 10 4 times.
2.5 10 10 10 10
We can group the 10s to make it a little easier to solve.
2.5 (10 10 10 10)
2.5 10000
Then, we can carry on multiplication as normal.
2.5 10000 = 25000
2.5 * 10^4 in standard form is 25,000.
Hope that helped =)