For many engineering problems, within 10% is "close". That would make

What constitutes "close to 1" depends on the application of the number. If it is reliability you are concerned about, and if lives are at stake, you may want reliability on the order of

999999999/1000000000 or better.

**9/10**"close to 1." Other times, you want at least 3-digit accuracy, so**9995/10000**would be a better candidate for "close to 1."What constitutes "close to 1" depends on the application of the number. If it is reliability you are concerned about, and if lives are at stake, you may want reliability on the order of

999999999/1000000000 or better.