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CTET Paper I (Classes I to V) Feb 2014 Solved Paper

Question : 55 of 150

Marks: +1, -0

The number of factors of 42 is

Solution:

Concept:

The total number of factors of a number is found by prime factorisation and using the formula: if

N = a^x \times b^y \times c^z

, then number of factors =

(x+1)(y+1)(z+1)

Explanation:

First, write 42 as a product of its prime factors.

42 = 2 \times 3 \times 7

Each prime appears only once, so exponents are 1.

Number of factors =

(1+1) \times (1+1) \times (1+1) = 2 \times 2 \times 2 = 8

Answer:

The number of factors of 42 is 8 (Option B).

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