**HCF**and

**LCM**of the numbers 60 and 72.

Start by writing each number as a product of its prime
factors.

60 =2×2×3×572 =2×2×2×3×3

To make the next stage easier, we need to write these so
that each new prime factor begins in the same place:

60 =2×2×3×572 =2×2×2×3×3

All the "2"s are now above each other, as are the
"3"s etc. This allows us to match up the prime factors. The highest
common factor is found by multiplying all the factors which

appear in both lists:

So the HCF of 60 and 72 is2×2×3which is12.

The lowest common multiple is found by multiplying all the
factors which appear in either list:

So the LCM of 60 and72is2×2×2×3×3×5which is360.