A human cell has about 3 billion base pairs of DNA.
The rate of substitution mutations in cells is about 1 per 108 (100 million) base pairs of nucleotides.
Therefore, each cell division yields about 30 mutations.
Your average cell has divided about 47 times from a single zygote.
After 47 divisions, your average cell has accumulated about 1,410 mutations.
You have 100 trillion (1014) somatic cells (chapter 13).
You have a total of 141,000 trillion, or 141 quadrillion (141 x 1015) mutations in your cells, not counting gametes.
This also does not count insertions, deletions, and other chromosomal damages.
©Copyleft Peter Chen