USGS topo maps have different line weights for contours at 20' and 100' multiples. I can use the Spatial Analyst contour tool to create contours at 20' intervals and again at 100' intervals and display them at different weights. Is there a way to do this with a single layer by somehow selecting the multiples of 100' and assigning them a different symbology? Alternatively, can I import the layer twice and use a query to select only the 100' multiples? I don't see how to do this? Perhaps I have to compute a new column that is true if it's a multiple of 100' and false if not?