I didn't even attempt to work it out, I just looked at the index of Hawking's "A Brief History Of Time" as I knew it was in there.
His "8 minutes" obviously doesn't satisfy the nitpickers.
Not as old as I feel. In six years at secondary school I had two years of imperial units (foot poundals etc) then two years of cgs (ergs etc) followed by two years of mks (joules etc).
However, 93 million miles divided by 186000 miles per second still gives the same answer of 8.3 minutes!