How to Calculate Variance and Standard Deviation $-$ a step$-$by step example

Olick to start. Then click on each step below to calculate standard deviation.

The following column shows the return on IBM stock in a recent $12-$month period

$\backslash$table$[[$Month$,\backslash$table$[[$IBM$],[$Return$,\%]],\backslash$table$[[$Deviation from$],[$average return$]],\backslash$table$[[$Squared$],[$deviation$]]],[1,2\mathrm{.}79,2\mathrm{.}20,4\mathrm{.}85],[2,-1\mathrm{.}57,-2\mathrm{.}16,4\mathrm{.}65],[3,6\mathrm{.}47,5\mathrm{.}88,34\mathrm{.}60],[4,-2\mathrm{.}02,-2\mathrm{.}60,6\mathrm{.}78],[5,8\mathrm{.}85,8\mathrm{.}26,68\mathrm{.}27],[6,-3\mathrm{.}09,-3\mathrm{.}68,13\mathrm{.}52],[7,5\mathrm{.}31,4\mathrm{.}73,22\mathrm{.}33],[8,-5\mathrm{.}84,-6\mathrm{.}43,41\mathrm{.}37],[9,0\mathrm{.}69,0\mathrm{.}10,0\mathrm{.}01],[10,-5\mathrm{.}67,-6\mathrm{.}26,39\mathrm{.}19],[11,-0\mathrm{.}77,-1\mathrm{.}36,1\mathrm{.}85],[12,1\mathrm{.}90,1\mathrm{.}32,1\mathrm{.}73],[$Total ${?}^3,7\mathrm{.}05,,239\mathrm{.}15],[$Average$,0\mathrm{.}59,$Variance $=19\mathrm{.}93,$Std deviation $=4\mathrm{.}46\%$