Apple’s OS X text-to-speech supports reading some big numbers. But they have to draw the line somewhere, and that line is just before one hundred sextillion. You can hear for yourself using the handy OS X “say” command.

Bare digit strings

Numbering on bare digit strings stops at one million.

$ say 1000000

You hear: “one million”

$ say 1000001

You hear: “one zero zero zero zero zero one”

Formatted number strings

Nicely formatted number strings get a bit more scale:

$ say "99,999,999,999,999,999,999,999"

You hear: “ninety-nine sextillion, nine hundred ninety-nine quintillion, nine hundred ninety-nine quadrillion, nine hundred ninety-nine trillion, nine hundred ninety-nine billion, nine hundred ninety-nine million, nine hundred ninety-nine thousand, nine hundred ninety-nine” (No, I didn’t type that out.)

But if you try adding 1…

$ say "100,000,000,000,000,000,000,000"

You hear: “one zero zero comma zero zero zero comma zero zero zero comma zero zero zero comma zero zero zero comma zero zero zero comma zero zero zero comma zero zero zero”