The interest you earn by intially investing some money is called as Simple interest.

If Principal = P, Rate = R% per annum, Time = T years, then

```
Simple Interest (S.I) = P * T * R / 100
```

P = 100 x S.I.

R = 100 x S.I.

and T = 100 x S.I.

```
Amount (A) = Principal(P) + Interest(I)
```

We can correlate it as

```
A = P + P * T * R/100
```

Or,

A = P(1 + T * R/100)

When type of interest is not specified, it is assumed to be simple interest.