Found this calc I did in 2008 ...
"The blogger writes: 'He ran a total of 17,500,000 miles in one hundred-thousandth of a microsecond. Multiply that by one hundred thousand to get the distance he can run in one second, and then that by sixty by the distance he can run in one minute, and then that by sixty again to get his mph. I got 6,300,000,000,000,000,000,000mph. 6.3 sextillion miles per. That’s 34,054,054,054,054,054 times the speed of light.'
That's not what I got. The blogger made 2 errors.
1. Assuming Flash carried two people at once, he made 250,000 70-mile roundtrips. That's 17,500,000 miles (so far so good). Now the blogger makes his first mistake: 17,500,000 miles x 100,000 x 3600 = 6,300,000,000,000,000 or 6.3 quadrillion (not septillion) miles per hour. Let's simplify by keeping it per second: 17,500,000 x 100,000 = 1,750,000,000,000 or 1.75 trillion miles. Divide this by 186,000 and you get 9.4 million cee: far, Far, FAR less than what the blogger posted.
But all is not lost.
2. Second error: Flash carries two people at once, making 250,000 70-mile roundtrips for a total of 17,500,000 miles in .00001 (1/100,000th) of a microsecond, which is already 1/1,000,000th (.000001) of a second. So the blogger is wrong when he says "Multiply that by one hundred thousand to get the distance he can run in one second." Actually, multiply by 10^11 (100 billion) to see what Flash ran in one second.
This comes out to 1,750,000,000,000,000,000 (about 1.75 quintillion) miles in 1 second. Divide 1.75 quintillion by 186,000 and you get about 9.4 trillion cee. If Flash carried one person at a time, you get about 19 teracee.
Again, far, Far, FAR less than 34 quadrillion cee, but still very impressive."
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Clearly the writer didn't know what he was writing or didn't care. Too bad. He threw all those cool numbers in, which gave the feat an air of realism. It's one of the best speed feats I'm aware of, especially since it wasn't a simple, straightforward run: Flash was lifting and carrying people, safely, over and over and over.