1 Samuel 30:12 KJV - And they gave him a piece of a cake of figs, and two clusters of raisins: and when he had eaten, his spirit came again to him: for he had eaten no bread, nor drunk any water, three days and three nights.
Job 2:13 KJV - So they sat down with him upon the ground seven days and seven nights, and none spake a word unto him: for they saw that his grief was very great.
Jonah 1:7 KJV - Now the LORD had prepared a great fish to swallow up Jonah. And Jonah was in the belly of the fish three days and three nights.
Exodus 24:18 KJV - And Moses went into the midst of the cloud, and gat him up into the mount: and Moses was in the mount forty days and forty nights.
Matthew 12:40 KJV - For as Jonas was three days and three nights in the whale's belly; so shall the Son of man be three days and three nights in the heart of the earth.
Day = 24 hour period, day = sunlight portion of Day, night = dark portion of Day
It's been said that any portion of a Day is reckoned as a whole Day. Just like for Jesus' duration in the grave, some argue that he did not have to remain in the grave for the duration of 72 hours. Thus, three days and three nights is not a literal expression. Does this same notion apply to other passages that specify X days and X nights?