To find the percentage change from 2500 to 900, we need to first calculate the difference between the two numbers.

Step 1: Difference = Final Value - Initial Value

Difference = 900 - 2500

Difference = -1600

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 = |-1600|

Absolute Difference = 1600

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

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

Percentage Change = (1600 / 2500) x 100

Percentage Change = 64%

Therefore, the percentage change from 2500 to 900 is -64%. This means that there was a decrease of 64% from 2500 to 900.