Is that any particular shape?
I think you mean "What is a mnemonic chart" and that is a variation of words that you write down to remember :)
Joey borrowed the money for 4 months. 2000 multiplied by .05 comes out to 100 which is the 5% so for him to get to 400 he had to owe the money for 4 months to pay 400 in interest. Hope this helps.