How many commandments did God write on the two stone tablets?

Answer: 10

The covenant words written on two tablets of stone are called the Ten Commandments.

“So Moses was there with the LORD forty days and forty nights without eating bread or drinking water. He wrote on the tablets the words of the covenant—the Ten Commandments. He declared to you His covenant, which He commanded you to follow—the Ten Commandments that He wrote on two tablets of stone.”— Exodus 34:28; Deuteronomy 4:13 (BSB)