Question 55192
Factoring Intergers
factor 140 in to the product of primes.
140
:/\
14*10
:/\*/\
(2)*(7)*(2)*(5)
The prime factors of {{{highlight(140=2*2*5*7)}}}
:
find the GCF for 40, 160, & 72.
If you can't look at the numbers and tell what divides evenly into all three, then break them up into their prime factors.  The GCF would be all of the prime factors that all three numbers have:
{{{40=highlight(2*2*2)*5}}}
40
:/\
(5)*8
..../\
....4*(2)
.../\
..(2)*(2)
--
{{{160=highlight(2*2*2)*2*2*5}}}
160
:/\
10*16
/\****/\
(2)(5)4*4
,,,,,/\*/\
,,,,(2)(2)*(2)(2)
--
{{{72=highlight(2*2*2)*3*3}}}
72
/\
9***8
/\***/\
(3)(3)(2)*4
,,,,,,,,,,/\
,,,,,,,,,(2)(2)
40,160, and 72 all have 2*2*2=8 in common.  Therefore {{{highlight(8)}}} is their GCF.
Happy Calculating!!!