I could go through and answer it all and give you the answer but i think this will be better. Scientific Notation is just a way to sum up a long number so you don't have to write out a bunch of zeros. Without talking about "significant figures" you just put a decimal point after the first actual number, add a "x 10" then count the zeros and write the number as a superscript to the 10. any number like this 0.000.... (smaller than 1) has a negative superscript. any number like 10000... (larger than 1) has a positive superscript.
Example:
6,200,000 = 6.2 x 10^6
&
0.0000062 = 6.2 x 10^-6
Here are some general rules now that you know what you are trying to do:
1. Scientific Notation ONLY ever has ONE number in front of the decimal, like this: 6.02 x 10^23.
NOT LIKE THIS: 60.2 x10^23 or 61.2 x 10^23
and NEVER a zero like this: 0.70 x 10^23.
2. it is ONLY ever a multiplication symbol, 6.02 "x" 10^23, NEVER divide, + or -.
3. for the examples on this paper, do NOT include zero's on the end like this 7.20 x 10^23. Only the actual numbers, and, zeros that are between numbers like this 6.0201 x 10^23. The zero's on the end get summed up and are noted in the ^23 part. (This part is called a superscript, in case you didn't know that)
4. In the last section they are just showing you some incorrect stuff to trick you up. Just put the decimal in the correct place and adjust the ^23 superscript bit.