How many stamps do I need to send an envelope with 5 sheets of paper from Manhattan to Albany, New York? It's a standard white envelope.?

Same answer as the one on the exact question you posted yesterday and then decided to delete.  5 sheets of paper plus envelope is typically just over 1oz which is the limit for a first class stamp.  "How many stamps" is not relevant since stamps have different value.  You need a total of 70 cents in postage.  That's 55 cents for standard first class up to 1oz and 15 cents per oz over that first oz.

(If you have Forever Stamps, then you can put two on and be overpaying since each of those currently are worth 55 cents.)

Probably 1 or 2, but it's based on weight and thickness, not number of sheets.

70 one cent stamps, or two "forever" stamps. old post office joke: lady says "I want to mail this letter." it has one stamp on it. Postal worker says "This letter weighs too much. It'll need another stamp." Lady then asks "Will that make it lighter"?

Put 3 stamps to be on the safe side, but 2 probably would be enough.