Question

How many megagrams are there in 7.020 * 10^-10 nanograms

Answer 1

7.020 * 10^-25
 There are 15 orders of magnitude between megagrams and nanograms Megagram = 1 x 10^6 gram
 Nanogram = 1 x 10^-9 gram

Answer 2

From the basics conversions:
1 nanogram is equivalent to 1 * 10^-15 megagrams

To convert 7.02 * 10^-10 nanograms to megagrams, all you have to do is cross multiplication as follows:
1 nanogram ................> 1 * 10^-15 megagrams
7.02 * 10^-10 nanograms ...............> ?? megagrams

megagrams = (7.02*10^-10 * 1*10^-15) / (1) = 7.02 * 10^-25 megagrams