Shortcut Trick
Required numbers must be exactly divisible by the LCM of 6, 12, and 16, which is 48.
Multiples of 48 between 400 and 600 are 48 × 9, 48 × 10, 48 × 11, and 48 × 12.
Required Sum = 48 × (9 + 10 + 11 + 12)
Required Sum = 48 × 42 = 2016
∴ The correct answer is 2016.
Alternate Method
Given:
Divisors = 6, 12, and 16
Range = Numbers strictly between 400 and 600
Concept Used:
A number is exactly divisible by a set of given numbers if it is a multiple of their Least Common Multiple (LCM).
Calculations:
⇒ Prime factorization of 6 = 2 × 3
⇒ Prime factorization of 12 = 22 × 3
⇒ Prime factorization of 16 = 24
⇒ LCM(6, 12, 16) = 24 × 3 = 16 × 3 = 48
⇒ We need to find all multiples of 48 that lie between 400 and 600.
⇒ Dividing 400 by 48, we get a quotient of 8.
⇒ The first multiple greater than 400 = 48 × 9 = 432
⇒ The maximum multiple less than 600 = 48 × 12 = 576
⇒ The valid numbers are: 432, 480, 528, 576
⇒ Sum of these numbers = 432 + 480 + 528 + 576 = 2016
∴ The correct answer is 2016.
Additional Information
Least Common Multiple (LCM)
The smallest positive integer that is uniformly divisible by two or more numbers. It is obtained by taking the highest power of each prime factor involved in the numbers.
Sum of Arithmetic Progression (A.P.)
Consecutive multiples of a number always form an Arithmetic Progression. The sum can also be calculated using the formula: Sn = n ÷ 2 × (first term + last term). Here, 4 ÷ 2 × (432 + 576) = 2 × 1008 = 2016.
Divisibility Rule
For a number to leave no remainder when divided by a group of divisors, it must be completely divisible by their LCM. If a remainder 'R' is specified, the general format of the number becomes (LCM × k) + R.