To find the percentage change from 70 to 100, we need to first calculate the difference between the two numbers.

Step 1: Difference = Final Value - Initial Value

Difference = 100 - 70

Difference = 30

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 = |30|

Absolute Difference = 30

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

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

Percentage Change = (30 / 70) x 100

Percentage Change = 42.86%

Therefore, the percentage change from 70 to 100 is 42.86%. This means that there was an increase of 42.86% from 70 to 100.