### About the Number 40 (forty)

This nBAB was created as a result of MathBabbler working on a BAB about the 40th anniversary of Apollo 8, which entered lunar orbit on 24 December 1968.

```   MathBabbler Number Analyst (MBNA) output:
=========================================
40 is a natural, whole, integer
40 is even
40 proper divisors are: 1,2,4,5,8,10,20,
40 is refactorable (evenly divisable by # of divisors)
40 is abundant (sum of divisors is 50)
40 is unhappy
40 is a Harshad number
40 is not prime
40 is undulating
40 has the prime factors: 2*2*2*5
40 in octal is 050
40 in hexadecimal is 0x28
40 in binary is 101000 (is evil)
40 nearest square numbers: -4...9 (36...49 [7])
sqrt(40) = 6.32456
ln(40) = 3.68888
log(40) = 1.60206
40 reciprocal is .02500000000000000000000000000000
40! is 8.15915e+47
40 is 12.7324 Pi years
40 is 2 scoreyears
40 written as a Roman numeral is XL
```

Why is forty not spelled "fourty?"

`[Wikipedi]` Negative forty is the temperature at which the Fahrenheit and Celsius scales correspond (i.e. `-40°F = -40°C`)

The entrance door to CM-473 at Scottsdale Community College needs a hit of WD-`40`.

`40` days... `40` nights... `40` winks... I-`40`... `40` years (ruby anniversary)... `40` hour work weeks...

Added the song titles "`40`" (by U2) and "`#40` (by Dave Matthews Band) to Songs With Numbers In Their Titles. In addition, the band names Crush `40` and UB`40` were added to Bands With Numbers In Their Names.

##### Update::2009.08.15

`40` years ago on 8/15/1969, the Woodstock Festival began.

`40` in base-11 in repdigit number 44 in base-10.

MathBabbler was `40`13 (i.e. 52) years of age when he updated this nBAB.

Creator: Gerald Thurman [gthurman@gmail.com]
Created: 25 December 2008