The limit is based on weight -- one ounce maximum. Two standard sheets will almost
certainly weigh less than one ounce, but I found that my Christmas cards plus a
2-page letter was too heavy. Three thin sheets might be under an ounce- you would
have to weigh it for sure.
Postage scales are not very expensive, and they have a free one at the PO.--I think that mine has probably paid for itself more than once is saving on postage.
By the way , the second ounce only costs 17 cents extra- I know people who put
a second 42-cent stamps just to make sure.
With a 42 cent stamp in the United States, you can typically mail one standard-letter-sized envelope that weighs up to 1 ounce. The number of pages you can include in your envelope will depend on the paper thickness, but as a general rule, you can usually include about 4-5 pages.
The Ship - novel - has 256 pages.
The Ship of Ishtar has 230 pages.
Plague Ship has 192 pages.
The Sorcerer's Ship has 205 pages.
The Mad Ship has 400 pages.
The Elfin Ship has 338 pages.
The Last Ship has 624 pages.
Ship of Magic has 667 pages.
The Ship Who Sang has 248 pages.
Ship of Destiny has 592 pages.
Ambulance Ship has 184 pages.
Pluto Saves the Ship has 51 pages.