7x6=42 80x6=480 400x6=2400 2400+480+42=2922
Of course there is no way to write them all because there are an infinite number of them.Start with 400x1=400Next 400x2=800Then 400x3=1200.Keep going with 400x4, 400x5, 400x6 etc.In general the multiples of 400 are written as 400k for natural numbers k=1,2,3...