1 + 1 != 3 only because we agree on notation to represent the real, physical world; "right" and "wrong" aren't in the same category, because they're matters of opinion, and for practical purposes on the time scale of individual human lives, might indeed does make right.
Example: Under the Fugitive Slave Act of 1850, if an enslaved worker escaped and fled north, anyone who helped him or her — even in a free state — could be arrested and fined; that was the law of the land for years, and it was deemed meet and right by enslavers and their sympathizers.
It's true that, in the long run and in some respects, "right" does seem eventually to converge on what humans generally agree on. But as John Maynard Keynes famously said (about investing for the long term), in the long run we are all dead — the U.S. Army's eventual vindication of "right" about slavery, in 1861-65, came too late for the millions of enslaved blacks who'd already died in the preceding 340-plus years.