Given, a,b and c are natural numbers. 1. LCM of (ab,ac)=abc a×LCM of (b,c)=abc Hence, statement 1 is correct. 2. HCF of (ab,ac)= Common factor of (ab,ac)=a and a×HCF(b,c)=a× common factor of (b,c)=a Hence, statement 2 is correct. 3. We know that HCF is always less than LCM. Hence, statement 3 is correct. 4. HCF(a,b) divides LCM(a,b) because a common factor between a,b always divides (a×b). Hence, statement 4 is correct.