Question

What is the least common multiple of 31, 28, and 14?

Answer 1

⇨ By prime factorization method:

$\begin{array}{r | l}{\sf{2 & {\sf14,28,31} \\\cline{2-2} {\sf2 & {\sf7,14,31 \\\cline{2-2} {\sf7 & {\sf7,7,31 \\\cline{2-2} {\sf31 & {\sf1,1,31 \\\cline{2-2} & {\sf1,1,1\end{array}$

${\sf{LCM\: = \:2 \:x\: 2 \:x\: 7 \:x\: 31}}\\\\{\sf{LCM \:= \:868}}\\}\\{\sf{Therefore,}}\\\\{\sf{LCM\:(14,\: 28,\: 31)\: = \:868$

${\boxed{\sf{LCM\:=\:868}}$