"The number of messages I sent yesterday was less than the messages I sent three days ago, and more than the messages I sent ten days ago."
How many consecutive days can someone make this statement given that it is true?
Not so many days.
A total of 7 days to be exact.
Your number will have to be gradually smaller to stay smaller than 3 days ago, but when that first value of 3 days ago becomes the value of 10 days ago, it will be too high. 10-3 = 7 days.
Example : 0-0-0-0-0-0-0-9-9-8-8(TODAY)-7-7-6-6-5-5.
EDIT:
It is actually possible to get an 8th day by using a simple trick. 1 day ago and 3 days ago are odd, but 10 days ago is even, so by creating 2 chains, we can make it so the number from yesterday be from a high chain and the the value from 10 days ago be from a low chain
Example : 0-0-0-0-0-0-0-9-19-8-18(TODAY)-7-17-6-16-5-15-4