American Standard Version
Doubtless , thou knowest, for thou wast then born, And the number of thy days is great!

Berean Study Bible
Surely you know, for you were already born! And the number of your days is great!

Douay-Rheims Bible
Didst thou know then that thou shouldst be born ? and didst thou know the number of thy days?

English Revised Version
Doubtless, thou knowest, for thou wast then born, and the number of thy days is great!

King James Bible
Knowest thou it, because thou wast then born? or because the number of thy days is great?

World English Bible
Surely you know, for you were born then, and the number of your days is great!

Young's Literal Translation
Thou hast known -- for then thou art born And the number of thy days are many!

Job 38:21 Additional Translations ...