Convert these numbers between standard form and normal numbers

Question 1:

6.72× 10 3
6720

Question 2:

7.73× 10 4
77300

Question 3:

8.5× 10 -3
0.0085

Question 4:

90100
9.01× 10 4

Question 5:

2550000
2.55× 10 6

Question 6:

0.000617
6.17× 10 -4