For any two numbers, the product of their LCM and HCF is equal to the product of the numbers themselves. Calculation: Let the two numbers be 3 x and 7 x The LCM of these Numbers =630 ⇒ We can express the LCM as LCM = Product of Numbers/ HCF But first, let's express LCM directly for the two numbers in the simplest form as LCM of 3x and 7x=21x ⇒21x=630 ⇒x=30 So, the numbers are 90 and 210 Now the HCF of 90 and 210 is 30 (since x=30 ) Now, add the LCM and HCF: ⇒630+30=660.