Can you solve this in 30 seconds?

We have a game on TV in the UK called countdown it's open to any age group and one of the two contestant yesterday was a schoolboy who did this in under 30 seconds.

The game is about making anagrams for the most part and one part is a math game.

The target number yesterday was 813

and you have to reach that figure using only these numbers, you dont have to use them all if you dont want and you can only use a number once.

on the programme you get 30 seconds, how long will it take you?

Your numbers are: 100, 75 50 25 10 1