Convert countdown to minutes and seconds

Question

I am looking for a way to convert a 4-digit countdown into minutes. meaning instead of going like this "302, 301, 300, 299..."
I want it to go "302, 301, 300, 260, 259...."

Answer 1

Actually, 300 should go to 259 as 260 means 300.

Answer 2

Never depend on anyone to do your code. Unless you have attempts and just need some assistance.
Study.