Each year the necklace gains 2.5% of its own value. To write a percentage as a decimal number, we just divide it by 100.
Since each year the necklace gains 2.5% of its own value, this means that each year we multiply the previous price by 100% plus this rate, which is
then, the value after one year is given by
and every year that passes, we multiply by this factor
The amount of times we multiply, is the amount of years that passed. Since we want to know the price after 10 years, the calculation is
The price after 10 years will be $1062.47.