This is a arithmetic progression issue. The initial value is 500, the arithmetic difference is 50, and the sum of series is 500n+25n(n- 1), where n is the number of months. A year is 65438+ February, so the total after one year is 500 *12+25 *12 *1= 9300. Similarly, ten years later, the total amount was 4 1.7 million, accounting for 4 1.7 million; Twenty years later, the total is 6.5438+0.554 million; By analogy, if you want to calculate the total amount after many years, just substitute the corresponding n into 500n+25n(n- 1), where n is the number of months experienced.