Biblical typology is the study of words, events, symbols, etc. that have a broader meaning then their immediate literary context. Numbers connected to events are the most common types found in the Bible; there were forty days of rain, forty years in the Sinai wilderness, forty days fasting in the desert etc.. It tells us that these events are connected or somehow foreshadow each other. Other important numbers include 1, 3, 7, 8, and 12.
Probably the best book on the subject is The Bible and the Liturgy by Jean Danielou. He looks into the Bible for events that foreshadow Catholic liturgy. One example he explores is the narrative of the flood and how it foreshadowed baptism. The ark going through the water represented the purification of mankind just as for those being baptized, water represents purification from original sin.
Also, he points out that the number of people on the ark is eight, the number that represents the new creation, the eighth day. Sunday is considered the eighth day as the day of Christ’s resurrection. (Danielou makes an interesting observation that there is no record of any dissent by Jewish Christians in the first century when they made Sunday rather than Saturday the day of worship). This is why in most Catholic churches the baptismal fonts are octagonal (at least at the time he wrote the book — 1956). Baptism removes the stain of original sin enabling a new creation.