80 (number) facts for kids

Eighty is a special number that comes after 79 and before 81. It's an even number, which means you can divide it by two without anything left over. Eighty is also a composite number, because it has more than two factors.

You can divide 80 by many other numbers, like 1, 2, 4, 5, 8, 10, 16, 20, and 40. Of course, you can also divide it by 80 itself!

Eighty in Math and Science

Eighty is often used in different areas of mathematics and science.

Number Properties

• Eighty is a Harshad number because it can be divided by the sum of its digits (8 + 0 = 8, and 80 ÷ 8 = 10).
• In Roman numerals, 80 is written as LXXX.
• It's a perfect totient number, meaning the sum of its totients is 80.

Element 80: Mercury

In chemistry, the chemical element with atomic number 80 is Mercury.

• Mercury is a unique metal because it's a liquid at room temperature.
• It's also known as quicksilver.
• Mercury has been used in thermometers and other scientific tools, but it's important to know that it can be poisonous.

Eighty in Everyday Life

You might see the number 80 in many places around you.

Time and Speed

• A famous adventure story is Around the World in Eighty Days by Jules Verne. It's about a character who tries to travel around the entire Earth in just 80 days.
• Speed limits on roads are sometimes 80 kilometers per hour (km/h) or 80 miles per hour (mph) in different countries.

Age and History

• When someone says "fourscore," they mean 80. For example, in Abraham Lincoln's famous Gettysburg Address, he started with "Four score and seven years ago..." which means 87 years ago.
• The 1980s (often called "the eighties") was a decade known for its unique music, fashion, and technology.

Other Uses

• In computer science, 80 is sometimes used in port numbers for HTTP (web traffic).
• Many video games or board games might use 80 as a score or a number of items.

Images for kids

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  Element 80: Mercury (Hg)

See also

In Spanish: Ochenta para niños