32=16x2=2x2x2x2x2=2^5
48=24*2=6x4x2=2x3x2x2x2
Pick the highest number that occurs. In this case it is 2. Now we have to see how many times it appears in both. It appears 5 times in 32 and 4 times in 48. 4 is the highest number of times it appears in the numbers so:
2^4=2x2x2x2=16
The Greatest Common Factor (GCF) of 32 and 48 is 16.