Standard form is a way of writing really big numbers in what is often a more compact manner. It also makes a really large number more readable. To put a number in standard form we write it by having a number between 1 and 10 and then multiply it by some (correct!) power of 10. So in this instance we're asked to put 800 million into standard form. 800 million as a number is written 800 000 000 we can see that if we take 8 as the digit then certainly we can multiply it by some power of 10 to make it 800 000 000. We realise that since there are 8 zeroes following the 8 in the number 800 million that the correct power of 10 is 10^8. So we can write our answer as 8 x 10^8.