headliner clips

Getting ready to have a headliner put in my wife's 70 Dart, how many of the little black clips are needed? Lost the ones we had and I need to know how many to get. Thanks in advance.

My 69 Barracuda 2-door hard top had 4 on one side, 3 on the other. These are about 1/4" wide and 1/2" long with a holding capacity of 0.100" - 0.200" (about 3/32" to 7/32").