In the context of DNA strand pairing, there is a specific pairing sequence. Adenine (A) will always pair with thymine (T); cytosine (C) will always pair with guanine (G). One strand goes from 5' to 3' and the pair strand goes from 3' to 5'. In this case, 1 and 2 pairs with each other as well as 3 and 4.
5'-AATTCCGGCCTAACTT-3' is paired to 5'-AAGTTAGGCCGGAATT-3'
5'-TTAAGGCCGGATTGAA-3' is paired to 5'-TTCAATCCGGCCTTAA-3'
