This math topic focuses on calculating the growth of money through simple interest, specifically concentrating on increments by 5% multiples. It involves finding the final amount when a principal sum has grown by 25% in interest. Each problem provides a starting principal amount (in dollars), and learners are required to calculate how much that amount increases when 25% interest is added. The topic is aimed at building fluency in understanding percent increase and its practical application in financial contexts like interest earnings.