The number of a man’s days is great if he reaches a hundred years: Compare Psa 90.10. Good News Translation is good here. Another approach is:

• A hundred years is as long as anyone could possibly hope to live.

Quoted with permission from Bullard, Roger A. and Hatton, Howard A. A Handbook on Sirach. (UBS Helps for Translators). New York: UBS, 2008. For this and other handbooks for translators see here.