20% of 320 is 64. This can be calculated by multiplying 320 by 20/100 or by dividing 320 by 5 and then multiplying by 1. Another way to think about it is to recognize that 20% means 20 out of 100, so 20% of 320 is the same as taking 20 out of every 100 parts of 320, which gives 64.