One that starts with 5 1 1 will be sold on Friday, and will not enjoy interest for three days on Friday, Saturday and Sunday. But if you buy it on Friday, you can enjoy interest on Friday, Saturday and Sunday.
Another one starts with 159. This is definitely no interest on the day of purchase, and definitely no interest on Friday, Friday, Saturday and Sunday. If you sell it on Friday, you will definitely enjoy interest on Friday, but I am not sure whether you will enjoy it on Saturday and Sunday. I will enjoy it with great probability.