72

72 (seventy-two) is a positive integer following 71 and preceding 73. Its ordinal form is written "seventy-second" or 72nd.
== Properties ==
72 is an .
MathWorld, Rule of 72 is a method for estimating the time required for a given principal to double. It is calculated as t = ln 2 / (ln(1+r)) and can be approximated as \(t \approx 0.72/r\). It is especially used in finance to estimate an investment's doubling time. For example, when the rate is 6%, 0.72/0.06 = 72/6 = 12 years is required to double the investiment, where the actual value is about 11.896.
== In googology ==
In Greek-based number-naming systems, 72 is associated with prefix "duheptaconta-", and with prefix "duoseptuaginti-" in Latin systems.
== In shogi ==
It is also the number of possible pawn moves (by a given player) in shogi.
== In TV broadcasting ==
In the Americas, the mid gap in the starts at 72 MHz.
== Sources ==
Category:Numbers
Category:Achilles numbers
Category:Class 1
Category:Even numbers
Category:Numbers 0-99
Category:Numbers in engineering
Category:Numbers with 1 to 2 digits