Carlton wears an assortment of sweater vests and button-up shirts. He has twice as many sweater vests as button-up shirts and considers each unique combination of vest and shirt to be an outfit. He owns three button-up shirts. How many outfits does Carlton have?
Carlton has 2 * 3 = <<2*3=6>>6 sweater vests.
He can wear each sweater vest with different 3 button-up shirts, so Carlton has 3 * 6 = <<3*6=18>>18 outfits.
#### 18