The claim

“what are the odds of you actually exsisting? is it 400,000,000,000,000 i think it is”

There is no single, scientifically agreed number for the “odds you exist,” and the specific figure 400,000,000,000,000 is not a standard or verifiable estimate.

Claims about the “odds of you existing” vary wildly because they depend on what is being counted (e.g., probability your parents meet, probability of a particular sperm fertilizing a particular egg, or probability of your exact genome and life history). Popular figures like “1 in 400 trillion” are usually rhetorical and come from stacking many speculative assumptions, not from a measured, reproducible calculation. While it is true that the number of possible sperm–egg combinations alone is extremely large (typically hundreds of millions of sperm per ejaculation), turning that into a precise probability of “you” requires additional assumptions about timing, fertility, partner choice, and identity criteria. Because the claim provides a precise number without defining the model or assumptions, it cannot be confirmed as a factual statistic.