Hallel with a Minyan
It is a mitzvah to daven with a minyan (ten men thirteen years of age or older), and according to one opinion it is a mitzvah de’Oraysa, a Biblical obligation, to daven with a minyan on Yom Tov. Davening with a minyan on Rosh Chodesh, when “half” Halel is said, is especially important, and there is even an opinion that Halel does not require a brocho unless it is said with a minyan. The Midrash tells us, “Ein Halel pachos mishlosha”, it is not considered Halel when said with fewer than three people. When a person is saying Halel privately the Halacha is that he should ask two Jews—it can be his wife and a child—to respond each time he recites the verse “Hodu La’shem ki tov ki l’olam chasdo”, as is normally done in shul. However, he is not required to search for people outside his home or immediate vicinity.
https://halacha2go.com?number=162