How do you write #2.8 * 10^9# in standard form?
Moving from scientific notation to standard notation involves:
First - write down the "number part" of the notation, like this:
Then move the decimal the number of places asked for. Positive exponents move the decimal to the right and negative to the left. Our question has the exponent 9, so let's move the decimal 9 places to the right (we're going to need to add 0's to do this!)
The decimal moved 9 places to the right from it's original place between the 2 and the 8 (I added the extra 0 at the end of the number to show where the decimal is. Normally we wouldn't put the 0 there - it's just to show in this example where the decimal ended up!)