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Real Numbers — Maths STD 10 — Question

CBSE BoardEnglish MediumSTD 10MathsReal Numbers3 Marks
Question
Explain why 3 × 5 × 7 + 7 is a composite number.
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Answer

Main Concept:A number which is not prime is composite.
3 × 5 × 7 + 7 = 7[ 3 + 5 + 1] = 7[15 + 1]
= 7 × 16 have prime factors = 7 × 2 × 2 × 2 × 2
So, number (3 × 5 × 7 + 7) is not prime hence, it is composite.

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