To find the percentage change from 2500 to 3500, we need to first calculate the difference between the two numbers.

Step 1: Difference = Final Value - Initial Value

Difference = 3500 - 2500

Difference = 1000

Step 2: Next, we need to find the absolute value of the difference. This is because percentage change is always calculated as a positive value.

Absolute Difference = |Difference|

Absolute Difference = |1000|

Absolute Difference = 1000

Step 3: Now, we can calculate the percentage change using the formula:

Percentage Change = (Absolute Difference / Initial Value) x 100

Percentage Change = (1000 / 2500) x 100

Percentage Change = 40%

Therefore, the percentage change from 2500 to 3500 is 40%. This means that there was an increase of 40% from 2500 to 3500.