A human cell has about 3 billion base pairs of DNA.
The rate of substitution mutations in cells is about 1 per 108 (800 million) base pairs of nucleotides.
Therefore, each cell division yields about 3.75 mutations.
Your average cell has divided about 47 times from a single zygote.
After 47 divisions, your average somatic cell has accumulated about 176 mutations.
You have 100 trillion (1014) somatic cells (chapter 13).
You have a total of 2,800 trillion, or 2.8 quadrillion (2.8 x 1015) mutations in your cells, not counting gametes.
This also does not count insertions, deletions, and other chromosomal damages.