To find the percentage change from 100 to 170, we need to first calculate the difference between the two numbers.

Step 1: Difference = Final Value - Initial Value

Difference = 170 - 100

Difference = 70

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 = |70|

Absolute Difference = 70

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

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

Percentage Change = (70 / 100) x 100

Percentage Change = 70%

Therefore, the percentage change from 100 to 170 is 70%. This means that there was an increase of 70% from 100 to 170.