### About the Number 80 (eighty)

MathBabbler posted a nBAB for the number 31 and he noticed he didn't have a nBAB for the number 30. He did have nBABs for 10, 20, 40, 50, 60, 90, 100, 200, 500, 1500, 1600, 1700, 1800, 1900, 2000, 2100 and 8100. MathBabbler opted to created this nBAB about the number `80` because his mom turned `80` this year (2009). Note: Barbara Walters turned `80` in 2009 and Martin Luther King Jr. would have turned `80` if he was still alive.

```   MathBabbler Number Analyst (MBNA) output:
=========================================
80 is a natural, whole, integer
80 is even
80 proper divisors are: 1,2,4,5,8,10,16,20,40,
80 is refactorable (evenly divisable by # of divisors)
80 is abundant (sum of divisors is 106)
80 is unhappy
80 is not prime
80 is undulating
80 has the prime factors: 2*2*2*2*5
80 in octal is 0120
80 in binary is 1010000 (is evil)
80 nearest square numbers: -16...1 (64...81 [9])
sqrt(80) = 8.94427
ln(80) = 4.38203
log(80) = 1.90309
80 reciprocal is .01250000000000000000000000000000
80! is 7.15695e+118
80 is 25.4648 Pi years
80 is 4 scoreyears
80 written as a Roman numeral is LXXX
```

I-`80` connects San Francisco, California to Fort Lee, New Jersey.

`[exercise]   ` `80` take-away the square number 16 equals the square number 64 and the square-root of 64 is 8 which is a factor of `80`.

`[exercise]   ` `80` divided-by 10 equals 8 which is 10 in base `80` divided-by 10.

##### Update::2009.09.05

MathBabbler's mom turned `80` years of age on 5 September 2009.

Note: The following information in this update was obtained from MathBabbler's MBNA (MathBabbler Number Analyst) program.

`80` is a triple-X Roman numeral because it (`LXXX`) contains three consecutive exes.

`80` in base-11 in repdigit number 88.

log5(`80`) = 2.72271 rounded to the nearest hundredth (2.72) equals e (2.71828183) rounded to the nearest hundredth (2.72).

log15(`80`) = 1.61815 rounded to the nearest thousandth (1.618) equals phi (1.61803399) rounded to the nearest thousandth (1.618).

Creator: Gerald Thurman [gthurman@gmail.com]
Created: 25 February 2009 (posted 27 February 2009)