[SeekAndFind]

FOR THOSE OF YO WHO ARE LUCKY TO HAVE A FULL TIME POSITION IN THE OBAMA ECONOMY:

Converting your salary to an hourly figure

You’re a salaried employee and trying to figure out how much that wage earns you an hour, maybe for that part-time job you’re considering taking on. Take your salary, drop the last three zeros and then divide by the number two.

So if you earn $40,000, you’re left with $20 an hour.

Numbers work best if you’re only working a 40 hour week.

[KarlInOhio]

1) The Rule of 72
3) The Rule of 70

These are basically the same whether you are figuring out how long it takes to double your money or for your money to halve by itself. The actual number is log(2)/log(1+R/100).

The rule of 72 is more accurate for 5% and above.

[Buckeye McFrog]

1) The Rule of 72

Need an easy way to determine how long it will take to double your returns? Simply divide the number 72 by your projected growth rate.

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Learned that one as a kid on an old rerun of The Lucy Show where she was trying to scam a double-your-money-back offer on baked beans.

[TurboZamboni]

The rule of 70 dictates how long it will take for inflation to halve the value of a dollar.

Simply divide 70 by your expected rate of inflation
mulitiplied by years Obama is in office.

[I_be_tc]

Later for numbers

[quintr]

math tricks

[zeugma]

Here's an interesting mathematical oddity that I learned about a few months ago...

Take any number.

If the number is even, divide by 2

if the number is odd, multiply by 3, then add 1

Take the result and process it in the same way.

You will eventually end up at 1

Here's the series you'd have if you start with the number 13:

13 40 20 10 5 16 8 4 2 1

Starting with 12:   12 6 3 10 5 16 8 4 2 1

This is called the Collatz Conjecture. The article in Wikipedia is really interesting.

Check out the number of steps for startnig numbers of 26, 27, and 28. 

26 13 40 20 10 5 16 8 4 2 1

27 82 41 124 62 31 94 47 142 71 214 107 322 161 484 242 121 364 182 91 274 137 412 206 103 310 155 466 233 700 350 175 526 263 790 395 1186 593 1780 890 445 1336 668 334 167 502 251 754 377 1132 566 283 850 425 1276 638 319 958 479 1438 719 2158 1079 3238 1619 4858 2429 7288 3644 1822 911 2734 1367 4102 2051 6154 3077 9232 4616 2308 1154 577 1732 866 433 1300 650 325 976 488 244 122 61 184 92 46 23 70 35 106 53 160 80 40 20 10 5 16 8 4 2 1

28 14 7 22 11 34 17 52 26 13 40 20 10 5 16 8 4 2 1

When I first started playing with this, I started looking at some of the interesting patterns and properties associated with it. I wrote a few shell scripts to look at different aspects of it. One interesting point is that when you are calculating the sequence for a particular number, once you hit a number you've already done, since you already know the 'path' taken from that number, you can stop and just refer to it rather than confinue along. This really sped things up once I started incorporating that into my shell scripts.
 

[Osage Orange]

1 + 1 = 0 after taxes..........