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How many 3 digit numbers are there with no digit repeated |
| Answer» Dear.. this question can be solved by using the fundamental principle of counting.... You can observer that we need a 3 digit number.. Thus we require ones\' digit, tens digit and hundred\'s digit... starting from that of hundreds digit.. We can put 1,2,3,3....9 in hundreds digit... it means we have 9ways.... then coming to tens digit... we can put 0,1,2,3....9 excluding the number we took at hundredth place... thus again we will have 9 ways.. Now one\'s digit... we can put 0,1,2...9 excluding the digits or numbers we used at the tens and hundredth places... thus we will have 8 ways... Hence the total no. Of ways = 9×9×8=648.... I hope it\'s clear... | |