He live to be 100 years old.

He lived until 100 years.
He lived until 100 years old

He lived until he was 100 years old.

None are correct.

#1 would be correct if you made the verb past tense instead of present tense: He lived to be 100 years old.

You could also write any of these:

He lived to be 100.
He lived until he was 100 years old.
He lived until he was 100.

Thank you for your help.

* He lived to be 100.

1. He lived until 100 years old.
2. He lived until 100.
3. He lived until 100 years.

Are they all wrong? Ungrammatical?

All are incorrect:

1. He lived until 100 years old.
2. He lived until 100.
3. He lived until 100 years.

This is correct:
He lived to be 100.

The correct way to express someone's age is "He lived to be 100 years old." This sentence indicates that the person reached the age of 100 before passing away.

To find out information about someone's age, you can often rely on biographical sources such as books, articles, or interviews. These sources usually provide information about a person's life, including their birth and death dates. You can consult reliable biographies, obituaries, or official records to learn the accurate age of someone at the time of their passing. Additionally, family members, friends, or other acquaintances may have personal knowledge about the person's age.