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Ridhi starts her factor tree for 100 with , while Sameer starts his with . What happens once both trees are finished?

Class 6Playing with NumbersPlaying with Numbers
  • ARidhi's tree ends up with more prime factors than Sameer's.
  • BBoth end with the same primes, .
  • CRidhi ends with and Sameer with .
  • DOnly Sameer's tree reaches prime factors at all.

Step-by-Step Solution

breaks down into , and breaks down into . Where you start the tree makes no difference — a number has just one prime factorisation. The trap is the third option, which stops while 4 and 25 are still composite.
Answer: B) Both end with the same primes, .

Key idea: Prime vs composite

A whole number greater than 1 is **prime** if it has exactly two factors: 1 and itself. It is **composite** if it has more than two factors. The number 1 is neither prime nor composite (it has only one factor — itself). 2 is the only **even** prime; every other even number is divisible by 2 and so has at least three factors.

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