News and Views

Today is “Pi Day”, the day we celebrate the relationship between the circumference and diameter of a circle. Can you guess why? Some people on this day mark the time of 1:59:26 as Pi second. I’m afraid that time has already passed as I write this, unless you live well west of Arizona.

Pi is an irrational number, meaning it cannot be expressed as the ratio of two integers. For most practical purposes, however, it can be approximated by 22/7. In fact, in England they sometimes celebrate Pi Day as July 22.

Pi is used in advanced applications far beyond this simple diameter-circumference relationship. It turns up in physics, electronics, geometry, trigonometry, number theory, astronomy, biology almost all branches of science, engineering and art.

Pi has been calculated to over a trillion digits by computer, but this is only an interesting mathematical exercise. With only about 39 digits, given the exact diameter of the universe you could calculate it’s circumference to the width of a hydrogen atom. For most household purposes 3.14 is sufficient, accurate to better than 1/10 of a percent.

Here’s more info on Pi, and on Pi Day

Here’s Pi to a few significant digits (I haven’t memorized it quite this far yet):

3.1415926535897932384626433832795028841971693993751058209 7494459230781640628620899862803482534211706798214808651 3282306647093844609550582231725359408128481117450284102 7019385211055596446229489549303819644288109756659334461 2847564823378678316527120190914564856692346034861045432 6648213393607260249141273724587006606315588174881520920 9628292540917153643678925903600113305305488204665213841 4695194151160943305727036575959195309218611738193261179 3105118548074462379962749567351885752724891227938183011 9491298336733624406566430860213949463952247371907021798 6094370277053921717629317675238467481846766940513200056 8127145263560827785771342757789609173637178721468440901 2249534301465495853710507922796892589235420199561121290 2196086403441815981362977477130996051870721134999999837 2978049951059731732816096318595024459455346908302642522 3082533446850352619311881710100031378387528865875332083 8142061717766914730359825349042875546873115956286388235 3787593751957781857780532171226806613001927876611195909 2164201989380952572010654858632788659361533818279682303 0195203530185296899577362259941389124972177528347913151 5574857242454150695950829533116861727855889075098381754 6374649393192550604009277016711390098488240128583616035 6370766010471018194295559619894676783744944825537977472 6847104047534646208046684259069491293313677028989152104 7521620569660240580381501935112533824300355876402474964 7326391419927260426992279678235478163600934172164121992 4586315030286182974555706749838505494588586926995690927
210797509302955321165344987202755960236480665499119