# Time at which price doubles in inflation.

by PhysicoRaj
Tags: doubles, inflation, price, time
 P: 121 anybody knows how to calculate the period which a commodity which faces inflation takes to double it's price, without knowing anything except the rate of inflation? You must give a very shortcut method. Thanks.
 P: 15 If X is the rate of inflation - 100/x
 P: 121 Thanks.
P: 1,958

## Time at which price doubles in inflation.

 Quote by Bignose If X is the rate of inflation - 100/x
Actually, a much better approximation is the "rule of 72", which is that the number of years to double at an annual growth rate of x% is 72/x. This is because (1+p)^n ~ e^(np), and ln(2) = .69. A slight correction makes it 72 instead of 69. Try it. You'll find that (1+p)^(72/p) ~=2.0 for a wide range of p.
P: 121
 Quote by phyzguy Actually, a much better approximation is the "rule of 72", which is that the number of years to double at an annual growth rate of x% is 72/x. This is because (1+p)^n ~ e^(np), and ln(2) = .69. A slight correction makes it 72 instead of 69. Try it. You'll find that (1+p)^(72/p) ~=2.0 for a wide range of p.
At last!!!!!!
I was waiting for someone who told me this rule! I wanted to know if this was familiar to all. Cheeeerup!!
 P: 15 Is inflation compounded though? my dollar stays a dollar year to year if I hold on to it. If I take 2% off and its... I guess it makes sense to compound an inflation rate. Stupid trick question.
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P: 4,972
 Quote by PhysicoRaj At last!!!!!! I was waiting for someone who told me this rule! I wanted to know if this was familiar to all. Cheeeerup!!
Indirection is sleazy. If you want to know something on this forum, just ask.

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