SSC CGL 2025 PYQ — Question 83

SSC CGL - 16 Sep 2025 - Shift 2 • Reasoning • Q83

In a certain number system there are only two notations to represent numbers: $\triangle$ and $\beta$ .

0 is represented by $\triangle$ and 1 by $\beta$ . The subsequent numbers are represented in the following manner:

2 is represented as $\beta$ $\triangle$ ,

3 is represented as $\beta$ $\beta$ ,

4 is represented as $\beta$ $\triangle$ $\triangle$ ,

5 is represented as $\beta$ $\triangle$ $\beta$ and so on.

How will you represent 81 in the given number system?

Show answer & explanation

Correct answer: D

Explanation

The correct answer is option 4 i.e. $\beta$ $\triangle$ $\beta$ $\triangle$ $\triangle$ $\triangle$ $\beta$ .

The logic followed here is:

This is a binary-like number system where:

Δ = 0

β = 1

Numbers are represented in binary form using Δ and β instead of 0 and 1.

Convert 81 to binary:

81 ÷ 2 = 40 remainder 1
40 ÷ 2 = 20 remainder 0
20 ÷ 2 = 10 remainder 0
10 ÷ 2 = 5 remainder 0
5 ÷ 2 = 2 remainder 1
2 ÷ 2 = 1 remainder 0
1 ÷ 2 = 0 remainder 1

So, binary (from last to first remainder) = 1010001

Replace 1 → β and 0 → Δ

Binary 1010001 → βΔβΔΔΔβ