The earth’s inner core is a solid ball of iron, nickel and other metals, while the outer core is liquid metal composed of iron and nickel as well. The temperature of the inner core is estimated to be about 5,400 degrees C or 9,800 degrees F, far beyond iron’s melting point.
The Mayan and other Mesoamerican cultures used a vigesimal number system based on base 20 (and, to some extent, base 5), probably originally developed from counting on fingers and toes. The numerals consisted of only three symbols: zero, represented as a shell shape; one, a dot; and five, a bar.
