I need to buy so many feet of a four foot wide material cut up cover thirty diameter round pool floor. How much do i buy?

To calculate the amount of four-foot-wide material you need to cover the floor of a thirty-diameter round pool, you need to first calculate the area of the pool floor. The formula for the area of a circle is:

```

Area = π * (radius)^2

```

where π is a mathematical constant approximately equal to 3.14 and the radius is half of the diameter. In this case, the diameter is 30 feet, so the radius is 15 feet.

Plugging this value into the formula gives:

```

Area = π * (15)^2

Area = 3.14 * 225

Area = 706.5 square feet

```

Since you are using four-foot-wide material, you will need to divide the area by the width of the material to determine the length you need to purchase.

```

Length = Area / Width

Length = 706.5 square feet / 4 feet

Length = 176.625 feet

```

Therefore, you will need to purchase approximately 177 feet of four-foot-wide material to cover the floor of the thirty-foot-diameter round pool.