जॉइन Examsbookउत्तर : 3. "243"
How many three digit numbers 'abc' are formed where two of the three digits are same ?5
प्र: How many three digit numbers 'abc' are formed where two of the three digits are same ?
- 1252false
- 2648false
- 3243true
- 4900false
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उत्तर : 3. "243"
व्याख्या :
Answer: C) 243 Explanation: Digits are 0,1,2,3,4,5,6,7,8,9. So no. of digits are 10 First all possible case => 9(0 excluded) x 10 x 10 = 900 Second no repetition allowed =>9 x 9 x 8 = 648 Third all digits are same => 9 (111,222,333,444,555,666,777,888,999) Three digit numbers where two of the three digits are same = 900 - 648 - 9 = 243 ;