The sum of three consecutive natural numbers each divisible by 3 is 72. What…
2025
The sum of three consecutive natural numbers each divisible by 3 is 72. What is the largest among them?
- A.
21
- B.
24
- C.
25
- D.
27
Attempted by 30 students.
Show answer & explanation
Correct answer: D
Solution: Interpret the phrase "three consecutive natural numbers each divisible by 3" as three consecutive multiples of 3.
Let the three consecutive multiples of 3 be 3k, 3k+3, and 3k+6.
Their sum is 3k + (3k+3) + (3k+6) = 9k + 9, and this equals 72.
Solve 9k + 9 = 72 → 9k = 63 → k = 7.
The numbers are 3·7 = 21, 3·8 = 24, and 3·9 = 27. The largest is 27.
Quick check: 21 + 24 + 27 = 72, so the answer is correct.