What is the importance of the number seven in the novel, We Are Seven?

The number seven symbolizes wholeness or completeness. In the Old Testament, it takes God seven days to complete his creation of the universe. Thus, the number seven represents a complete act, indeed a complete world, and carries with it a certain spiritual connotation. Likewise, the young girl insists that there are seven children in her family, in spite of the fact that two of them are dead. This is because seven also represents a sense of completeness to her, as seven is the number of children that were once in her family. If she were to believe that there were any fewer than seven children, then she would be acknowledging that her siblings John and Jane are dead and her family is incomplete.