This Bible contradiction is from the Skeptic's Annotated Bible.
On the first day of the first month.
Genesis 8:13 View context
And it came to pass in the six hundredth and first year, in the first [month], the first [day] of the month, the waters were dried up from off the earth: and Noah removed the covering of the ark, and looked, and, behold, the face of the ground was dry.
On the 27th day of the second month.
Genesis 8:14 View context
And in the second month, on the seven and twentieth day of the month, was the earth dried.