The HCF and LCM of two numbers are 30 and 840, respectively. If the first number is divided by 2, then the quotient is 60. The second number is:

HCF of two numbers = 30

LCM of two numbers = 840

First number / 2 = 60, therefore the first number is 120.

Product of two numbers = HCF × LCM

If the first number is a and the second number is b, then: a × b = HCF × LCM

As given ;

a = 60 × 2 = 120

as we know,

a × b = HCF × LCM

Substituting the values, we get:

120 × b = 30 × 840

120 × b = 25200

​$$b = \frac{25200}{120} = 210$$ ​

Thus, the second number is 210.