I thought he had a good point, but then I realized his intro test was rigged: twice he said "say them out loud", so I tried to memorize the sound of the numbers

I thought he had a good point, but then I realized his intro test was rigged: twice he said "say them out loud", so I tried to memorize the sound of the numbers. But then I thought about how I remember passwords, PINs, and phone numbers, and I don't memorize any of these by the sound of their digits (perhaps because it would be so inefficient in English!). I remember sequences of digits (or chars) by visualizing how I use them, i.e., spatially. In this case, I pretended the 7 digits made up a phone number and mentally placed them on a phone. Now I can't seem to forget 485-3976.