18 (عدد)

← 17 18 19 →
كميخطأ: الوظيفة "numeral_to_english" غير موجودة.
ترتيبي18
(خطأ: الوظيفة "numeral_to_english" غير موجودة.)
نظام العدoctodecimal
التحليل لعوامل2 × 32
القواسم1, 2, 3, 6, 9, 18
العدد اليونانيΙΗ´
العدد الرومانيXVIII
ثنائي100102
ثلاثي2003
رباعي1024
خماسي335
سداسي306
ثماني228
اثنا عشري1612
ستة عشري1216
عشرينيI20
أساس 36I36

18 (ثمانية عشر) هو عدد صحيح يلي العدد 17 ويسبق العدد 19 وهو عدد طبيعي موجب.

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في الرياضيات

  • ثمانية عشر هو عدد مؤلف، أي غير أولي، قواسمه هي 1، 2، 3، 6 و9. ثلاثة من تلك القواسم (3, 6 و 9) مجموعهم 18, ولذلك 18 هو semiperfect number.[1] Eighteen is the first inverted square-prime of the form p·q2.
  • In base ten, it is a Harshad number.
  • It is an abundant number, as the sum of its proper divisors is greater than itself (1+2+3+6+9 = 21). It is known to be a solitary number, despite not being coprime to this sum.
  • It is the number of one-sided pentominoes.
  • It is the only number where the sum of its written digits (1+8 = 9) is equal to half of itself (18/9 = 2).


في العلوم

الكيمياء

في الدين والأدب


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كرقم حظ أو نحس

  • In Chinese tradition, 18 pronounced 十八 (shí bā) and is considered a lucky number due to similarity with 實發 (shì fā) 'definitely get rich', 'to get rich for sure'.[3]
  • According to applications of numerology in Judaism, the letters of the word chai ("living") add up to 18. Thus, 18 is considered a lucky number and many gifts for B'nai Mitzvot and weddings are in $18 increments.[4]

عـُمْر 18

In most countries, 18 is the age of majority (adulthood) and also the voting age.

In eleven states of the United States, 18 is the age of sexual consent.

In most US states and pursuant to federal law, 18 is the minimum age to purchase firearms (with the exception of handguns) 18 is also the minimum age to get married without parental consent.

It is the minimum age at which one can purchase, rent, or buy tickets to NC-17-rated films or buy video games with an AO rating.

It is also the age of sexual consent under U.S. federal law (although this law only applies in circumstances involving transportation or transaction between different states or outside the United States).[5]

In addition, Pennsylvania has a corruption of minors law that makes the de facto age of consent there 18.[6] This is also the case in some jurisdictions outside the United States,[7] including Canada.[8][9]

في الرياضة

في المجالات الأخرى

ثمانية عشر هي أيضاً:


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انظر أيضاً

الهامش

  1. ^ "Sloane's A005835 : Pseudoperfect (or semiperfect) numbers". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation. Retrieved 2016-05-31.
  2. ^ N James. The Early Composition History of Catch-22. In Biographies of Books: The Compositional Histories of Notable American Writings, J Barbour, T Quirk (edi.) pp. 262-90. Columbia: University of Missouri Press, 1996
  3. ^ 言必有「中」:「十八」「實發」 人見人愛. 文匯報. Accessed 2015-01-12. Archived 2015-01-15.
  4. ^ "Chai, Its Meaning and Significance | Shiva, Jewish Mourning". www.shiva.com. Retrieved 2020-11-18.
  5. ^ "The US Federal Age of Sexual Consent". SOL Research. Retrieved 2013-08-02.
  6. ^ "Age Of Consent By State". Age-of-consent.info. Archived from the original on 2011-04-17. Retrieved 2013-08-02.
  7. ^ "Worldwide Ages of Consent". Avert.org. Retrieved 2013-08-02.
  8. ^ CANADA'S LEGAL AGE OF CONSENT TO SEXUAL ACTIVITY Revised 12 April 2001: "Section 153 now prohibits "sexual interference" or "invitation to sexual touching," in respect of a young person over 14 but under 18, where the accused is in a relationship of trust or authority towards the complainant or the complainant is in a relationship of dependency with the accused."
  9. ^ Government of Canada - Age of Consent to Sexual Activity: "the age of consent is 18 years where the sexual activity "exploits" the young person -- when it involves prostitution, pornography or occurs in a relationship of authority, trust or dependency (e.g., with a teacher, coach or babysitter). Sexual activity can also be considered exploitative based on the nature and circumstances of the relationship, e.g., the young person's age, the age difference between the young person and their partner, how the relationship developed (quickly, secretly, or over the Internet) and how the partner may have controlled or influenced the young person."
  10. ^ [1]
  11. ^ [2]
  12. ^ "Eighteen One-Name Study". One-name.org. 2012-01-13. Archived from the original on 2013-05-07. Retrieved 2013-08-02.