To find the percentage change from 40 to 50, we need to first calculate the difference between the two numbers.

Step 1: Difference = Final Value - Initial Value

Difference = 50 - 40

Difference = 10

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 = |10|

Absolute Difference = 10

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

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

Percentage Change = (10 / 40) x 100

Percentage Change = 25%

Therefore, the percentage change from 40 to 50 is 25%. This means that there was an increase of 25% from 40 to 50.