There are seven days in the week. Matthew and Mark tell us that Jesus fed four thousand people with seven loaves (Mat 15:36). The apostles, soon after Pentecost, appointed seven people to "serve at tables" (Acts 6:3). John described his vision of the end of time to "the seven churches in Asia" (Rev 1:4), and 54 of the 94 occurrences of the word "seven" in the New Testament occur in his account, in the last book in the bible, of how the world would end - revealed through the "seven spirits of God" in "the book with seven seals".
Jacob had twelve sons, founders of the twelve tribes of Israel. Jesus chose twelve disciples to follow him. There were twelve fragments of bread left over from the feeding of the five thousand. The tree of life in John's vision had "twelve kinds of fruit." (Rev 22:2).
Numbers - some numbers at least - had special meanings in days gone by. People saw connections based on numbers. God had perfected the work of creation, according to Genesis, in seven days, so seven stood for perfection. The Jewish law was enshrined in the first five books of the Bible, from Genesis through to Deuteronomy, the so-called Pentateuch. So when the disciples reported to Jesus that the five thousand hungry people only had five loaves (and two fishes) among them, readers might have said to themselves, "the law is enough, provided that Jesus is in charge."
You might like to work out for yourself what unites Noah's flood, Moses' journey to the promised land (and his time on Mount Sinai), Jesus' temptations and the period before "the time when Jesus was lifted up". (A prize for those whose answer lies somewhere between thirty and fifty!)
Any number might have a special meaning. The 1260 days mentioned in Rev 11:3 and 12:6 are 42 months, and 42 months are three and a half years - half of seven, the perfect number. Indeed the book of Revelation is full of "meaningful" numbers: the woman with the crown of twelve stars in Rev 12 recalling the tribes of Israel, the beast opposing her with the seven heads and ten horns, like the beast in Daniel 7, recalling people's search for patterns in the history of the Greek and Roman empires.
Revelation reminds us that numbers were also used to hide what could not be said openly. There were times when Christians had to be secretive about their views and their situation, to protect themselves and each other. They might have to witness to their faith in good deeds, and to confess it if challenged. But they would be foolhardy to be too plain in what they said. It was best to keep their thoughts about "the divine Caesar" to themselves. The beast in John's vision "whose number is six hundred and sixty six" was most likely a reference to the Emperor Nero.
How? Well, before the Romans came up with the idea of counting I II III IIII V, and long before the Arabs took over from the Indians a system of special characters, 1 2 3 4 5, the Hebrews and the Greeks had used a system where the numbers were represented by A B C D E and so on. N was fifty, and writing Neron Caesar in Hebrew letters produced a total of 666.
Peter caught 153 fish (Jn 21:11). Again, this number could well have been significant to listeners studying John's gospel. Ten and seven both suggest completeness, and adding all the numbers from one to seventeen yields 153. But we do not know if this is what John sought to say. And indeed we do not know that the beast in Revelation was a figure for Nero.
Just because the writers of apocalyptic books - Daniel and Revelation in particular - hid part of their message in case it fell into the wrong hands, it does not mean that the Bible is teeming with hidden messages which we do not know about. There are certainly a lot of interesting patterns - but we should beware of interpretations which are unfamiliar or unaccepted. We use the Bible to inform and broaden our faith, not to fish for ideas which are strange and which do nothing to make us better at serving God. In Jesus, God was made manifest - plain for all to know - and if we sincerely want to know God, there is, and can be, nothing hidden in the message the Bible gives us.
HD