In the spirit of the song "Echad - mi yodeya", please post interesting and significant Jewish facts about the number 0.5.
Lazy gematria may be worthy of discission, but perhaps not of a full-fledged answer.
Check out mi-yodeya-series for the previous three hundred forty eight entries in this ongoing series.
Please include sources for your information wherever possible, as with all other answers on this site.
I do not know why this number was omitted.
Yom Tov is regarded as Chatzi L'Hashem and Chatzi lachem (half for Hashem and half for you) - Refer to Gemoro Beitzah 15b
Machatzit hashekel (half a shekel) for counting Yisrael in the desert and payment for the hekdesh (money for the Temple).
Mincha Gedola starts half an hour after Chatzos.
Meguilat Esther 7:1 "What is your request, Queen Esther? It shall be granted you. Even if it be up to half the kingdom ("חצי המלכות"), it shall be fulfilled" (Artscroll Translation)
Half of man’s waking hours are spent praying, eating, and relieving himself:
כמה שנותיו של אדם שבעים שנה דל עשרין דלא ענשת עלייהו פשו להו חמשין דל עשרין וחמשה דלילותא פשו להו עשרין וחמשה דל תרתי סרי ופלגא דצלויי ומיכל ודבית הכסא פשו להו תרתי סרי ופלגא
How many are the years of man? Seventy. Subtract twenty, for which Thou dost not punish, [and] there remain fifty. Subtract twenty-five which comprise the nights, [and] there remain twenty-five. Subtract twelve and a half of prayer, eating, and Nature's calls, [and] there remain twelve and a half.
(Shabbat 89b, Soncino translation)
The demon of the bathroom escorts you for half a mil:
תנו רבנן הבא מבית הכסא אל ישמש מטתו עד שישהה שיעור חצי מיל מפני ששד בית הכסא מלוה עמו ואם שימש הוויין לו בנים נכפים
On coming from a privy a man should not have sexual intercourse till he has waited long enough to walk half a mil, because the demon of the privy is With him for that time; if he does, his children will be epileptic.
(Gittin 70a, Soncino translation)
"...He said to Isaac: Your children have sinned against Me. Isaac said before Him: Master of the Universe, are they my children and not Your children? At Sinai, when they accorded precedence to “We will do” over “We will listen” before You, didn’t You call them, “My son, My firstborn son Israel” (Exodus 4:22)? Now that they have sinned, are they my children and not Your children? And furthermore, how much did they actually sin? How long is a person’s life? Seventy years. Subtract the first twenty years of his life. One is not punished for sins committed then, as in heavenly matters, a person is only punished from age twenty. Fifty years remain for them. Subtract twenty-five years of nights, and twenty-five years remain for them. Subtract twelve and a half years during which one prays and eats and uses the bathroom, and twelve and a half years remain for them. If You can endure them all and forgive the sins committed during those years, excellent. And if not, half of the sins are upon me to bear and half upon You." (Shabbat 89b)
Yitzchak splitting the punishment years of Am Yisrael half-and-half between himself and Hashem.
Some people sit half an hour at the Chanukah candles after it is lit.
You can’t marry half a woman:
חצייך מקודשת לי אינה מקודשת
‘half of thee be betrothed to me,’ she is not betrothed.
(Kiddushin 7a, Soncino translation)
Shulchan Aruch Orach Chayim 486: Some hold that the size of Kezayis is half the size of a Kebeitza.
צרת רבים חצי נחמה While this normally is translated as the English statement "misery loves company," it literally means "suffering of the public is half of the comforting."
The concept of chatzi-shiur e.g. in Yoma 74a
כל היכא דתני ענוש כרת לא תני אסור והתניא אע"פ שאמרו אסור בכולן לא אמרו ענוש כרת אלא על האוכל ושותה ועושה מלאכה בלבד הכי קאמר כשאמרו אסור לא אמרו אלא בכחצי שיעור אבל כשיעור ענוש כרת ואף על פי שענוש כרת אין ענוש כרת אלא אוכל ושותה ועושה מלאכה בלבד
The Gemara’s initial assumption is that the mishna’s use of the word prohibited is referring to a transgression not punishable by karet. The Gemara asks: And anywhere that it teaches that transgressing is punishable by karet, does it never teach using the word prohibited? Was it not taught in a baraita: Although they said the word prohibited with all of the five Yom Kippur afflictions, they said that the punishment of karet applies only to one who eats, or drinks, or performs prohibited labor. This means that the word prohibit is used with transgressions punishable by karet as well. The Gemara rejects this. This is what the baraita is saying: When they said that those five activities are prohibited, they said that only with regard to a half-measure; but a full measure is punishable by karet. And although a violation is punishable by karet, it is punishable by karet only if one eats, or drinks, or performs prohibited labor; these alone are the cases where karet is incurred. (Sefaria translation and added notation)
The concept of מחצה על מחצה in shas e.g. in Bava Basra 23b:
מתני׳ ניפול הנמצא בתוך חמשים אמה הרי הוא של בעל השובך חוץ מחמשים אמה הרי הוא של מוצאו נמצא בין שני שובכות קרוב לזה שלו קרוב לזה שלו מחצה על מחצה שניהם יחלוקו
MISHNA: With regard to a dove chick [nippul] that was found within fifty cubits of a dovecote, it belongs to the owner of the dovecote. If it was found beyond fifty cubits from a dovecote, it belongs to its finder. In a case where it was found between two dovecotes, if it was close to this one, it belongs to the owner of this dovecote; if it was close to that one, it belongs to the owner of that dovecote. If it was half and half, i.e., equidistant from the two dovecotes, the two owners divide the value of the chick.
Hillel HaZaken would give half of his daily income in order to learn torah. See Yuma 35b:
אמרו עליו על הלל הזקן שבכל יום ויום היה עושה ומשתכר בטרפעיק חציו היה נותן לשומר בית המדרש וחציו לפרנסתו ולפרנסת אנשי ביתו פעם אחת לא מצא להשתכר ולא הניחו שומר בית המדרש להכנס עלה ונתלה וישב על פי ארובה כדי שישמע דברי אלהים חיים מפי שמעיה ואבטליון
They said about Hillel the Elder that each and every day he would work and earn a half-dinar, half of which he would give to the guard of the study hall and half of which he spent for his sustenance and the sustenance of the members of his family. One time he did not find employment to earn a wage, and the guard of the study hall did not allow him to enter. He ascended to the roof, suspended himself, and sat at the edge of the skylight in order to hear the words of the Torah of the living God from the mouths of Shemaya and Avtalyon, the spiritual leaders of that generation.
Not sure on top of my head the source. Roughly translates to 'A wise question is half the Answer'.
Concept that says only half the damage value are due in some instances, eg an ox that doesn't normally purposely damage (ב"ק פ"ה מ"א).
