How many 3 digit numbers have exactly 2 digits that are the same?

Answer 1

We have three cases:

1- Hundreds digit= Tens digit:

In every hundred 9 numbers are in this pattern:

110-112-113-114-115-116-117-118-119

and we have 9 hundreds, so in this case there are 81 numbers.

2- Hundreds digit= Units digit:

In every hundred 9 numbers are in this pattern:

101-121-131-141-151-161-171-181-191

and we have 9 hundreds, so in this case there are 81 numbers!

3- Tens digit= Units digit:

In every hundred 9 digits are in this pattern:

100-122-133-144-155-166-177-188-199,

and we have 9 hundreds, so in this case there are 81 numbers!

Total = 81 + 81 + 81 = 243

Answer 2

Oh, dude, let me break it down for you. So, there are 9 choices for the digit that's different from the other two, and 3 choices for where that different digit goes. That gives us 27 possible numbers with exactly 2 digits the same. Easy peasy, lemon squeezy.

Answer 3

To find the number of 3-digit numbers with exactly 2 digits the same, we can break it down into cases. There are 9 choices for the repeated digit (1-9, excluding 0), 8 choices for the non-repeated digit, and 3 positions for the non-repeated digit in the number (hundreds, tens, or units place). Therefore, the total number of such numbers is 9 * 8 * 3 = 216.

Answer 4

Answer is 243

Starting at 100 (the first 3-digit number), I counted all numbers that had exactly two digits that were the same. I did this through 199. There are 27 of these. I then multiplied that result by 9 (to pick up the 200s through 900s).

Answer 5

21