## Ratios.## They are everywhere. |

If Then Calculator (ITC) is not a calculator as we know it. It is designed only for calculating ratios(proportions).

ITC is inheriting its name from the simplest logic that we use in declaring ratios (If A is equal to B, Then C is equal to D).

The Wikipedial declaration of ratio is: *“A ratio is a relationship between two numbers.”*

Let’s imagine two numbers from any simple equation from life:

- You bought a box of candle for 15$.
- When you got home, you opened your box and there were 6 candles.
- What would you pay if you’ve bought 10 candles?

Here’s the logic:

If 6 candles is for 15 dollars.

Then 10 candles is for ? dollars.

That’s for direct proportion. If you get more, you must pay more. The result will appear as 25$.

Let’s take another sample for inverse proportion.

Here’s another logic:

- 3 friends built a sandcastle in 90 minutes.
- If there were 5 of them, how long would it take to finish?

Here, if you use direct proportion, the result will increase. But they are more people, shouldn’t they complete in shorter time?

So here you use inverse proportion and get the result of 54 mins.