Balaam’s Karbonos

When Balaam came to curse the Jews he build seven alters and sacrificed a bull and a lamb on each altar.  Later, when Balaam’s location was moved he built another seven altars and a sacrificed a bull and a lamb on each altar.  Balaam moved to a third location and built another seven altars and sacrificed the same number of bulls and lambs as he did each time before. 

Question: What is the total number of animals Balaam sacrificed? (Bamidbar 23:1)

Answer: 7 (alters) x 2 (animals) x 3 (locations) = 42