For any 2 numbers product of their LCM and HCF is equal to product of two given numbers.

I.e  L.C.M. × H.C.F. = Product of two given numbers

Since they are coprimes, so their HCF is 1

I.e  L.C.M. × (1) = Product of two given numbers

L.C.M. = Product of two given numbers

Therefore the Least Common Multiple (LCM) of two coprimes is always equal to their product.

For example, 8 and 9 are co-prime numbers. Hence, LCM (8, 9) = 72.

NOTE: 1 forms a co-prime number pair with every number.