I found this puzzle on another site so I put it here to share with you.
I will give link for the pattern logic of given puzzle.
Answer: Click here
The answer is
the first digit is the number of letters in the word "Sunday", the second digit is the position of Sunday in the week (starting from Monday), and the other digits are the sum of the first two.
This same pattern worked to generate all the other numbers for Monday to Saturday - check it!