The discussion of a non-literal interpretation of Genesis 1 doesn't need to bring in numbers. What we have to realize is who the audience was for this text and what they might have understood it to mean. Genesis 1 is not primarily about science or some evolution debate. Genesis 1 is about God.
Genesis 1 is a proclamation to the pagan nations. It is an apologetic text combating the competing creation myths. Instead of the world forming out of chaos and accident, it is formed by God's definite plan. Instead of the sun and the moon being gods themselves, they are creations of the ultimate God.
Genesis 1 is about two things, glorifying God and establishing the Sabbath. Trying to read our modern scientific debates into it isn't its purpose.
RE: Were the seven days of creation in Genesis seven twenty four hour periods? - Some conclusions