How Many Verses Must Be Read For Each Aliyah. Containing 6 Se'ifim:
On a day that 3 [people] read, we do not read less than 10 verses. [The frequent short introductory verse] "And [the Lord] spoke..." is included in the count [of verses]. And if the topic ends in less than 10 verses, for example the parsha of Amalek [Exodus 17:8] which has only 9 verses, it is acceptable.
Each person does not read less than 3 verses. Two read 3 each, and one reads 4, and whichever one of them it is who reads 4, behold this one is praiseworthy.
If one skipped a verse and didn't read it - if it was Mincha on Shabbos, or a Monday or Thursday, and they read 10 verses besides for the skipped verse, they do not need to go back [and repeat the reading], but if not, then they must go back. But if it was [the] Shabbos [morning reading], then even if he skipped one verse, he must go back and read again; even if they already returned the Torah [to the ark] and they said Kaddish, he must go back and read - the skipped verse and two others; and even if they [already] read the Haftarah (the reading from the Prophets) and prayed Mussaf, he must go back and read again. The Torah readings on the Festivals (their laws) are similar to Shabbos Mincha, Monday, and Thursday, since they already read those readings on their [respective] Shabbos.
If one person read [only] 2 verses, he needs to go back and read [again]. And if they only read 9 verses between the three of them, 3 for each of them, there is no need for them to go back and read [again]. And proof for this is the parsha of Amalek [Exodus 17:8-16] (which only has 9 verses). But if they read less than 9 they need to go back and read [again].
If one read the parsha of Parah and stopped [at the end of the tenth verse which concludes with the words] "ha'ger ha'gar be'tocham..." ("who lives among them..."), and rolled up the Torah scroll, he must go back, open it again, and start reading from the beginning of the parsha until [the verse which concludes with the words] "tit'ma ad ha'arev" ("shall be ritually unclean until the evening"), and he must make the blessing before and after it.
One who read from the Torah first, and the second [reader] read what the first had [already] read: if he added 3 verses to what was already read by the first, or even 2 verses in a place where it was not possible [to add 3], the second is included in the count [of valid aliyot]. But if not, he is not included in the count, except for [the reading of the portion of] the bulls of [Chol HaMoed] Chag (i.e. Sukkot) because there is no possibility [of adding additional verses].