Well, next year (2010) use 1760 and 1759!
And in 2011 use 1761 and 1760.
Bingo.
You can figure out the algebra yourself…
(hint: 2009-1759=250=550 and 250=100)
Let’s say X is the number you get in step 1.
And Y is your birth year
The equation they give us can be expressed thuswise:
(X*2+5)*50+1759-Y
If we multiply the 50 out using the distributive property we get:
X100+250+1759-Y
Note that 250+1759 = 2009. That’s why it only works this year.
X100+2009-Y
So, X*100 gives you your 1-digit number in the hundreds place
and 2009-Y gives your current age as a 2-digit number.
The whole “multiply by 2 then add five then multiply the result
by 50” thing is to obfuscate the simplicity of the equation
X*100+2009-Y
One morning, exactly at sunrise, a Buddhist monk began to climb a tall mountain. The narrow path, no more than a foot or two wide, spiralled around the mountain to a glittering temple at the summit. - The monk ascended the path at varying rates of speed, stopping many times along the way to rest and to eat the dried fruit he carried with him. He reached the temple shortly before sunset. After several days of fasting and meditation, he began his journey back along the same path, starting at sunrise and again walking at variable speeds with many pauses along the way. His average speed descending was, of course, greater than his average climbing speed. - Is there a spot along the path the monk will be on both trips at precisely the same time of day?