Question

What is the hcf and lcm of 90 and 126

Answer 1

LCM
1. Find the prime factorization of 90
2. 90 = 2 × 3 × 3 × 5
3.Find the prime factorization of 126
126 = 2 × 3 × 3 × 7
4.Multiply each factor the greater number of times it occurs in steps i) or ii) above to find the lcm:
LCM = 2 × 3 × 3 × 5 × 7
5.LCM = 630


HCF

1. Find the prime factorization of 126
   126 = 2 × 3 × 3 × 7
2. Find the prime factorization of 90
   90 = 2 × 3 × 3 × 5
3. To find the gcf, multiply all the prime factors common to both numbers:
   
   Therefore, GCF = 2 × 3 × 3
4. HCF = 18