Question

the number of 3-digit odd numbers when repetition of digits is allowed is​

Answer 1

Step-by-step explanation:

Let there be 3 slots for 3-digit odd number.

The digits used can be 0,1,2,3,4,5,6,7,8,9..

___,___,___

First slot:-

0 can't be used in the 1st slot

1,2,3,......, 9 can be used

No. of ways to fill 1st slot is 9

Second slot:-

0 can be used and repetition is allowed

0,1,2,3......,9 can be used

No. of ways to fill 2nd slot is 10

Third slot:-

Since it's a 3 digit odd number,

the last digit should be odd.

1,3,5,7,9 can only be used---5 ways.

No. of ways to fill 3rd slot is 5.

______,_______,______

9 ways×10 ways×5ways

Total=450 ways