What is the significance of numbers in the Bible

The people who wrote the books of the Old Testament, ancient Israelites, loved numbers. They are not unusual in this, many different nations loved numbers as well. This is important, when they mention a number it is usually has significance way beyond just counting. More than that, the significance of the number is probably more important than the literal number itself. So

1 = Wholeness
3 = a divine number, so Abraham was visited by three men, the Temple had three parts to it, the works of God could take three days - just like the resurrection. Time is also in three parts, God was and is and is to come.
4 = the number of the created world. There are therefore four seasons, four corners of the earth, four kinds of living creatures, four riders of the apocalypse, four winds,
6 = seven minus one,  a number of incompleteness. Six days of creation were incomplete until the seventh day had come.  So in Revelation six seals, trumpets represent the course of the world before Gods final seventh act brings the eternal sabbath.  So in spite of having seven heads the beats is number 666.  See why we must not take Revelation  literally!
7 = The sum of three plus four, the earth number and the divine number. It signifies perfection. There were seven heavenly bodies sun, moon and five planets, seven days of the week, seven archangels. The great festivals lasted seven days, every seventh year was a sabbath year when the land was laid fallow and slaves went free.  So Jesus says forgive seven time seven, which means always.  Later Christians tradition noted that the Gospels record seven last sayings of Jesus.
10= a round number, the fingers of both hands, good for commandments. Note that there were ten things God said at creation, so ten words to create were supported by ten words to keep order.
12 = there were 12 tribes - also a number of completion, so 12 x 12 is very complete (144)  which is the number of the elect, not literally but to show that no one is forgotten or lost. So there will be 12 cornerstones of the new Jerusalem
40 - a strictly limited period of time. It was the length of a generation.