How many 5 digit nos are there if the 2 leftmost digits are odd and the digit 4 can't appear more than once in the number ?
Could someone please provide a solution using a approach other than ( 1-x(none)) approach?
Choose the correct choice from the following options:
A) 24300
B) 25700
C) 26500
D) 24400
E) 26300
A. 4 is used once: OO**4 --&gt; (5*5*9*9)*3: 5 choices for the first digit as there are 5 odd numbers, 5 choices for the second digit for the same reason, 9 choices for one of the two * (not-4 digit), 9 choices for another * (not-4 digit), multiplied by 3 as 4 can take the place of any of the three last digits (OO**4, OO*4*, OO4**);   B. 4 is not used: OO*** --&gt; 5*5*9*9*9: the same logic as above.   5*5*9*9*3+5*5*9*9*9=24,300.   24300NSWER:24300
<result>A</result>
How many 5 digit nos are there if the 2 leftmost digits are odd and the digit 4 can't appear more than once in the number ?
Could someone please provide a solution using a approach other than ( 1-x(none)) approach?