The prime factorisation of 140 is
A$2 \times 5^2 \times 7$
B$2^2 \times 5^2 \times 7$
C$2^2 \times 5 \times 7$
D$2^3 \times 5 \times 7$
Answer & Solution
Correct answer: C. $2^2 \times 5 \times 7$
1. $140 = 2 \times 70 = 2 \times 2 \times 35 = 2 \times 2 \times 5 \times 7$.
2. Grouping: $140 = 2^2 \times 5 \times 7$.
3. Check: $4 \times 5 \times 7 = 140$ ✓.
_Source: Karnataka SSLC (KSEEB) Class 10 Mathematics, Ch8 'Real Numbers', §8.3_
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