You could do it simply, using Cascading Style Sheets (CSS) and some experimentation. An example to illustrate:
<!--- This part contains arbitrary page content --->
<!--- Display the 100 records here --->
Place the DIV element in the location of the page where you wish to display the records. Then experiment by increasing or decreasing the value of the CSS height attribute until there are exactly 18 records visible. Et voilà!