Mathematical Problems
Postman Pat ★★
Postman Pat delivers the mail in the small village Tenhouses. This village, as you already suspected, has only one street with exactly ten houses, numbered from 1 up to and including 10.
In a certain week, Pat did not deliver any mail at two houses in the village; at the other houses, he delivered mail three times each. Each working day he delivered mail at exactly four houses.
The sums of the house numbers where he delivered mail were:
on Monday: 18
on Tuesday: 12
on Wednesday: 23
on Thursday: 19
on Friday: 32
on Saturday: 25
on Sunday: he never works
The question: Which two houses did not get any mail that week?
