I recently read that there are a billion trillion stars in the known universe. How many zeros is that?

answers:
Ronald 7 say: How many hairs does a horse have ?

oldprof say: 21

az_lender say: 9 + 12 = 21

Jeffrey K say: 10^9 * 10^12 = 10^21
That is 21 zeros. But most estimates of the number of stars is greater than that.

Bulldog redux say: That would be 10^21.
