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Q76·CSAT · Prelims 2025

Code: 64 to 343, 216 to 729, find 512

ReasoningCoding-DecodingCoding-decodingMedium

Question

In a certain code if 64 is written as 343 and 216 is written as 729, then how is 512 written in that code?

Options

a

1000

b

1331

Answer
c

1728

d

2197

Explanation

Identify the mathematical nature of the numbers provided. All of them are perfect cubes. 64 = 4³ is coded as 343 = 7³. The base relationship is 4 \rightarrow 7 (an increase of +3). 216 = 6³ is coded as 729 = 9³. The base relationship is 6 \rightarrow 9 (an increase of +3). The code operates by taking the cube root, adding 3, and cubing the result. Apply this to the target number 512. 512 = 8³. Adding 3 to the base gives 8 + 3 = 11. Calculate the cube of 11: 11³ = 1331.

Always memorize perfect squares up to 30 and perfect cubes up to 15. Number coding questions that look like random large numbers are almost always disguised cube/square transformations.

Answer: (b).

Question details

Year

2025

Paper

CSAT

Question

Q76

Section

Logical & Analytical Reasoning

Sub-topic

Coding-Decoding

Type

Coding-decoding

Difficulty

Medium

Source hint

Coding pattern

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