n 1946, Albert Einstein said if he had known the Germans wouldn't succeed in constructing the atom bomb, he "would never have lifted a finger."

Did I punctuate correctly?

Yes.

To determine if you punctuated the sentence correctly, let's break it down and analyze the punctuation.

The given sentence is: "In 1946, Albert Einstein said if he had known the Germans wouldn't succeed in constructing the atom bomb, he 'would never have lifted a finger.'"

Here is the punctuation breakdown:

1. "In 1946" - This introductory phrase is correctly punctuated with a comma.
2. "Albert Einstein said" - Here, no punctuation is needed as it is a straightforward statement.
3. "if he had known" - This subordinate clause begins with "if" and requires a comma to separate it from the main clause.
4. "the Germans wouldn't succeed in constructing the atom bomb" - Again, no punctuation is required here as it is a direct statement.
5. "he 'would never have lifted a finger'" - This quote is enclosed in single quotation marks. The provided punctuation is correct, as long as single quotation marks are used consistently throughout the text.

Based on this analysis, it appears that you have punctuated the sentence correctly. Well done!