notation - Data Storage Question Help

Apologies if this question is in the wrong area, I'm fairly new here!
I'm currently studying a Computer Science degree and I'm so bad at Maths I should probably be ashamed. I'm learning, but since I'm teaching myself, this next part I'm totally confused as to whether I'm right or wrong. Any help would be really advantageous!

Question: An average of 48.8 million public photos were uploaded to the Flickr photo sharing website each month during 2013. If the average size of an uploaded photo is 3 MB, how much storage space does a month of uploaded public photos take up? Give your answer to 3.s.f in both Terabytes (TB) and bytes (b).

I know I have to use a scientific notation for this question but trying to work it out is confusing me! Here's what I've got so far!

1MB = 2^20 or 1,048,576
3MB = (2^20 x 3) or 3,145,728

So, to work out the above question

(2^20 x 3MB) x 48,800,000 (pictures)
=153,511,530,000,000 MB

To give my answer in TB (this is where I'm starting to get confused)

1 MB = 9.537109375E-7 TB
153,511,530,000,000 MB = 146405625.1934 TB

I suspect that the answer is right, I'm just not sure what the scientific notation is. I have no idea what E-7 means and I found that conversion from a data conversion website.

Then, when trying to convert it into bytes, I got some ridiculous number like

160968506081300000000 

Basically, i'm one very confused lady right now!

I'd be very grateful for some insight and criticism into where I'm going wrong!

Many thanks in advance,
Chloe