Metro systems of the World. World Metro System Facts. THE world's first metro, now the world's oldest system, is the London Underground in England, which is more commonly known as the Tube, which was opened in 1863. At 402 kilometers in length the London Underground is also the world's second longest metro system.
To find out if 90 is an even number, we divided 90 by two. When we did that, we found the answer to be a whole number. If you divide any number, such as 90, by two and you get a whole number, it means that the number is an even number.hen we did that, we found the answer to be a whole number. If you divide any number, such as 90, by two and you get a whole number, it means that the number is an even number.
There are few other numbers as small as 360 that have so many different factors. This makes the degree a very nice unit to divide the circle into an equal number of parts. 120 degrees is 1/3 of a circle, 90 degrees is 1/4, and so on. So while a deeg, being 1/100th of a circle, may seem nice and round to us ten-fingered folks, it isn't so convenient for dividing a pie into thirds.