42 (عدد)

42 (الثاني والأربعين) هوعدد طبيعي يلي العدد 41 ويسبق العدد 43.

هوالعدد الكاتالاني السادس في الترتيب.

مراجع

^ Alex Zhai ties for second-highest score in 2007 USA Mathematical Olympiad– By Andrew Lovdahl Gargoyle staff reporter Posted Monday, May 7, 2007, The OG, news & student awards – Online Gargoyle نسخة محفوظة 12 مايو2020 على مسقط واي باك مشين.
^ Cooper, Paul W. (1966). "Through the Earth in Forty Minutes". American Journal of Physics. 34 (1): 68–69. Bibcode:1966AmJPh..34...68C. doi:10.1119/1.1972773.
^ Carroll, Lewis (29 December 1893). "Chapter 7". سيلفي وبرونو. 2. illustrated by Harry Furniss. United Kingdom: Macmillan and Co. Each railway is in a long tunnel, perfectly straight: so of course the middle of it is nearer the centre of the globe than the two ends: so every train runs half-way down-hill, and that gives it force enough to run the other half up-hill.