Measuring how much things go up or down in percentage is really useful in our daily lives. I notice it a lot, like when prices change or when grades go up and down. Here’s how I think about it:

Understanding Percentage Increase

When I want to find out how much something has gone up, I use this easy formula:

Percentage Increase = (New Value - Original Value) ÷ Original Value × 100

Let’s say a shirt costs $200, and then it goes up to$250. Here’s how I calculate it:

Percentage Increase = (250 - 200) ÷ 200 × 100 = 25%

That means the price increased by 25%!

Understanding Percentage Decrease

Now, if something goes down, the formula is quite similar:

Percentage Decrease = (Original Value - New Value) ÷ Original Value × 100

If that shirt’s price drops to $150, I would do this:

Percentage Decrease = (200 - 150) ÷ 200 × 100 = 25%

So, the price went down by 25%.

Real-Life Applications

Here are some places I see this kind of math in real life:

1. Shopping: Finding out when things are on sale or how prices change.
2. Test Scores: Seeing if my grades get better or worse.
3. Finance: Understanding changes in my allowance or savings.

Seeing how these ideas work makes math more than just numbers. It helps me understand my everyday life better!