1) 7 to the power of 10 so basically it’s 7x7x7x7x7x7x7x7x7x7 so the property this is called is Scientific notation. So, if you want to divide powers you take away the bottom from the top so...
7x7x7x7x7x7x7x7x7x7
7x7x7x7x7x7
Then takeaway 6 from the bottom and six from the top which leaves you with 7x7x7x7 so another way of saying this is 7 to the power of 4 (7 with the small 4)
(Sorry I don’t know 2)
3) Scientific Notation is useful as you don’t have to keep writing the number over and over again. For example if you had 6 to the power of 27 your not going to write 27 6s.
Hope this can help!