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how many 3-digit numbers can be formed from the digit s 1,2,3,4,5,6 and 7, if each digit can be used only once?​

Sagot :

Answer:

Now, for 3 digited odd numbers, the digit occupying the units place must be 1,3 & 5. So with 1 at units place, the hundreds place can be filled by any of the 5 digits (excluding 0 and the odd digit 1 occupying the units place) in 5 ways and the tens place can be filled by any of the 5 digits (including 0 but excluding the digit occupying the hundreds place and 1 occupying the units place) in 5 ways. So for 1 in the units place, the number of 3-digited numbers is 5*5=25. The same analogy holds for 3 & 5 occupying the units place. Thus the total number of 3 digited odd numbers are 25+25+25=75.

Step-by-step explanation: