PSA Cert # Question

What are the first few digits I'd expect to see on a PSA cert # for a recently graded card? I know this has been asked before, and I searched for the thread but couldn't find it.

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It'd be nice if they included the date graded in the cert verification.
147
<< <i>So a 146 would have graded how long ago (approximately)? >>
February 1964
New is depicted by the # grade, below letter grade:
Old is on the same line:
<< <i>Then you have different label backs, but that's a whole other thread. >>
Not to mention old grades that have been reholdered in new slabs.