Is this a contradiction or am I reading it wrong? Genesis 5:28

[Ferrocyanide]

Doing the math is a fun exercise.
One person had said 3.25 times all the water in the oceans.
My number came up to 3.12.

Not even close. HE would need enough water to cover the entire earth to an elevation of 29,029 feet [8,848 meters] ASL*, to cover Everest.

*Above Sea Level.

Yes, I did include the height of Everest.
Try the math for yourself. See what you get. It is an interesting exercise no matter if you are an atheist, a yec, a oec, a 5 y old, a 10 y old, a 100 y old.

And if you are talking to a yec, you can explain to them the various details that make their belief a nonsense.