Think about the sequence 3'-T-C-T-C-T-A-C-G-T-5'
And its complimentary strand 5'-A-G-A-G-A-T-G-C-A-3'
What is the total number of covalent bonds joining the nucleotides in each strand?
What is the total number of noncovalent bonds joining the nucleotides of the complementary strands?