Opening letters
The letters that open twenty-nine surahs — الم, حم, يس, ق, ن — with what each comes to in abjad, and the fact that nobody claims to know what they mean.
Twenty-nine of the 114 surahs open with a short run of letters, recited as letter names rather than as a word: alif-lam-mim, ha-mim, ya-sin. They are called the muqattaʿat, the disconnected letters, and they use exactly fourteen of the twenty-eight — half the alphabet, which is why the tradition also calls them nisf al-huruf.
The table below gives each cluster, the surahs it opens, and its abjad total from the same arithmetic every other page here uses. الم comes to 71; حم to 48; ق, standing alone at the head of surah 50, to 100.
What the page does not do is tell you what they mean. That is not modesty — it is the majority position among the classical commentators, Ibn Kathir among them, that their meaning is known to God alone. Many readings have been offered and they contradict one another. Any site that gives you one and not the others is choosing for you.
Read across for the cluster, the surahs and the total, and check any of it: the letters are printed, the values are on the conventions page, and the text they are read from is the Tanzil edition this site ships with its checksum stated.
The totals are worth sitting with rather than acting on. They are what these letters come to under the same table that gives محمد 92 — no more and no less than that. Where a number here matches a total you have from elsewhere, that is arithmetic meeting arithmetic, and this site will not tell you it is more.