Question

List all integers between -15 and 25 that are congruent to 3 mod (11)

Answer 1

The positive ones (from 0 to 25) are easiest to start with, we want remained 3 upon division by 11.

3 is the first trivial choice since "three goes into 11 zero times with three left over" so

11 × 0 + 3 = 3
11 × 1 + 3 = 14
11 × 2 + 3 = 25

For the negative ones we want,
11 × -1 + 3 = -8