Question

What is the HCF / GCF of 120, 180 and 190

Answer 1

120 = 10 * 3 * 2 * 2
180 = 10 * 3 * 3 * 2
190 = 10 * 19

looks like 10

Answer 2

But the answer in the book is 6840 for HCF / GCF of 120, 180 and 190 calculated under prime factorisation method. How it is? Can someone explain the calculation in depth..!!

Answer 3

Sure, but that is the lowest common multiple

we need
one 10
one 19
two 2
two 3

10 * 19 * 2 * 2 * 3 * 3 = 6840