That is a good question. Why does GOD say this is a great miracle? The first thing you need to realize is GOD is telling you this is a great miracle in 74:30-37, not me. As well, the Quran commands us to verify all information as HE gave us the hearing, the eyesight and the brain and we are responsible for using them. So, the onus is on each of us to study it. You can find all the information hereas I only presented a small sliver of the math code in Quran.
Peace
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