Qm
Brainteasers

Three ages that add to 20 and multiply to 240

numbersagesfactorisationsearch

Three sisters have ages that are whole numbers. The ages add up to 20 and multiply to 240.

How old are the sisters? Show that the answer is unique by organising the search around the oldest sister's age rather than trying all combinations.

Show a hint

Factor 240 and look for three factors that add to 20. Use the prime factorisation 240 = 2 to the 4 × 3 × 5 to organise the search.

Your answer

Solving needs a free account

Answers, streaks and solutions unlock when you are signed in. Reading the question and the hint stays free.

Create a free accountSign in

Discussion

Sign in to join the discussion · reading is open to everyone

💡 Discussion rules

  1. No full solutions here. Hints and approaches only.
  2. Complexity, edge cases and intuition are the point.
  3. Interview experiences are welcome. Respect your NDAs.

Loading discussion…

Learn the concepts

The theory behind this question.

Balance-Scale Weighing ProblemsMastermind: Deduction From FeedbackSearching a Unimodal FunctionAdaptive Versus Pre-Committed Weighing StrategiesThe Lost Boarding Pass Problem

Related questions

The person whose age is the square root of the yearThe number equal to the sum of the cubes of its digitsThe number that equals the sum of the factorials of its digitsThe nine-digit number whose every prefix dividesThe two-digit number that is the square of its digit sum
All questions →