When the new value is greater then the old value it is a percentage increase otherwise it is a decrease. An important thing to remember is to cross-multiply after you have identified the different parts of the formula. Multiplying the result by 100 will yield the solution in percent rather than decimal form.
This process is the reverse of what you did earlier. Multiplying the result by 100 will yield the solution in percent rather than decimal form. Y2 - y1 y1100 your percentage change. To simply compare two numbers use the percentage calculator.