If a strand of DNA were composed of the base sequence of ATCG, what would be the complimentary sequence of its opposing base pairs?

The complementary strand would have the following sequence. TAGC

DNA is a double stranded molecule. The bases will pair with each other.

A-T G-C

A teacher I used to work with had a huge crush on George Clooney. She always joked that this helped her to remember the base paring rules. She would go on and on that she dreamed of being invited over to have dinner AT George Clooney's house.

This video shows an animated tutorial from PBS that can be helpful in better understanding how DNA copies itself because of these base pairing rules.

Hope this helps!