एक (3)-अंकीय संख्या (2,3,4,5,6,7) से बनानी है। संख्या (400) से कम हो और अंक दोहराए जा सकते हों। कुल कितनी संख्याएँ बनेंगी?
A (3)-digit number is formed from (2,3,4,5,6,7). The number must be less than (400), and digits may repeat. How many numbers are possible?
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Correct Answer
A. \(2 \times 6 \times 6=72\)
Concept
The hundred place can only be (2) or (3), and each remaining place has (6) choices. Apply the bound condition to the highest place.
Why this answer is correct
The correct answer is A. \(2 \times 6 \times 6=72\). The hundred place can only be (2) or (3), and each remaining place has (6) choices. Apply the bound condition to the highest place.
Exam Tip
सैकड़ा स्थान केवल (2) या (3) हो सकता है, बाकी दोनों स्थानों पर (6) विकल्प हैं। सीमा की शर्त सबसे बड़े स्थान पर लगाएँ।
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