Here's for future help as well scientific notation involves placing one number in front of a decimal fallowed by any number besides zero until there is none such as 87630 would be 8.763 x 10^4 because there is 4 numbers behind the original 8 so your 84000 eighty four thousand has 4 numbers behind the eight so you take you eight put it in front of your decimal like this 8. And since you have a 4 as well and four is not zero you put that behind the decimal 8.4 but all the rest are zeros so you don't include them but they are still numbers so you put 4 as your exponent so it would be 8.4 x 10^4
