The choice when expressing numbers is between using a word to express the number (e.g., three) or a figure (e.g., 3).  Please check whether or not the number is expressed correctly.  Then  highlight the rule that governs the use of the number in this instance.

A five page passage about Thiamin (Wentzler, 1980) was used for the material to be studied.

The expression of the number is   correct     incorrect       because: