Rule 1: Madd lāzim: always six counts
Madd lāzim comes in four kinds, named by two questions. Is it in an ordinary word (kalimī) or in one of the opening letters of a sūra (ḥarfī)? Is the sukūn after the madd part of a doubled letter (muthaqqal, "heavy") or a plain sukūn (mukhaffaf, "light")? Kalimī muthaqqal: a madd letter followed by a shadda in a word, as in اَلضَّالِّينَ, اَلْحَاقَّةُ, اَلصَّاخَّةُ. Kalimī mukhaffaf: a madd letter followed by a plain sukūn; it occurs in only one word, آلْآنَ, twice in Sūrat Yūnus (10:51 and 10:91). Ḥarfī muthaqqal: in the opening letters, a letter whose spelled-out name ends in a sākin letter that merges into the next letter, as the ل of الٓمٓ (lām-mīm, where the م of lām merges into mīm). Ḥarfī mukhaffaf: an opening letter whose name has a madd followed by a plain sukūn, as نٓ, قٓ, صٓ and the مٓ of الٓمٓ.
وَلَا الضَّالِّينَ
wa laḍ-ḍāllīn
nor of those who go astray
kalimī muthaqqal: ā followed by the doubled ل; six counts (1:7).
الٓمٓ
alif lām mīm
Alif, Lām, Mīm
لَآمّ is ḥarfī muthaqqal (its م merges into the next letter); مِيٓمْ is ḥarfī mukhaffaf; each six counts (2:1).
يسٓ
yā sīn
Yā, Sīn
يَا has two counts (no sukūn after it); سِيٓنْ is ḥarfī mukhaffaf, six counts (36:1).
نٓ
nūn
Nūn
نُوٓنْ: ḥarfī mukhaffaf, six counts (68:1).
قٓ
qāf
Qāf
قَآفْ: ḥarfī mukhaffaf, six counts (50:1).
آلْآنَ
āl-āna
now?
kalimī mukhaffaf: ā followed by a plain sukūn on ل; six counts (10:51).