Question

Below is a copy of a calendar for July 2015 .

Statement: The sum of any three dates in a row is always a multiple of 3.

(Do it algebraically and check if the given statement is true or false)

Answer 1

Let us consider any three dates in a row.

If we take the first number be x, then the second number must be 'x + 1' and the third one should be 'x + 2'.

Then the sum is

(x) + (x + 1) + (x + 2) = 3x + 3 = 3(x + 1)

We note that 3(x + 1) is a multiple of 3.

Hence the sum of any three dates in a row is always a multiple of 3.

Therefore the given statement is true.