SSC CHSL Tier-1 practice question
How many 3-digit (odd) numbers can be formed using the digits 1, 2, 3, 4, 5, 7, 9 without repetition?
From a SSC CHSL Tier-1 Quantitative Aptitude practice set · Quantitative Aptitude
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Correct answer: (B) 150
Fix the last (units) digit as odd first: 5 choices. The remaining 2 places are filled from the other 6 digits without repetition: 5 × ᴾ(6,2) = 150.
हिंदी में प्रश्न
अंकों 1, 2, 3, 4, 5, 7, 9 का प्रयोग करके बिना पुनरावृत्ति के कितनी 3-अंकीय (विषम) संख्याएँ बनाई जा सकती हैं?
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उत्तर और व्याख्या देखें
सही उत्तर: (B) 150
पहले अंतिम (इकाई) अंक को विषम तय करें: 5 विकल्प। शेष 2 स्थान अन्य 6 अंकों में से बिना दोहराव के भरे जाते हैं: 5 × ᴾ(6,2) = 150।
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