The HCF of two numbers is 7 and their LCM is 84 . If one of the numbers is 21 then find the other number.
Let the other number be a.
We know that,
(HCF of the two numbers) x (LCM of the two numbers)= Product of Two numbers
Now, 7×84=21×a
588=21a
Which on dividing both sides by 21 ,
We get, a=28
The other number is 28 .