Then the **circumference** (all the method around the circle) is **3.14159265...You are watching: What is pi divided by 2** a number known as

**Pi**

**Pi** (pronounced like "pie") is frequently written making use of the greek prize π

The definition of π is:

The **Circumference****divided by the Diameter****of a Circle.**

The circumference separated by the diameter the a one is always π, no matter how huge or little the circle is!

To help you psychic what π is ... Just draw this diagram.

## Finding Pi Yourself

Draw a circle, or use something circular favor a plate.

**Measure roughly the leaf (the circumference**):

**I got 82 cm**

Measure across the one (the **diameter**):

**I obtained 26 cm**

Divide:

82 cm / 26 cm = 3.1538...

That is quite close come π. Probably if i measured an ext accurately?

## Using Pi

We can use π to find a Circumference as soon as we know the Diameter

Circumference = π × Diameter

### Example: you walk about a one which has actually a diameter the 100 m, how much have girlfriend walked?

### Example: Sam measure 94 mm around the outside of a pipeline ... What is the Diameter?

## Radius

The radius is fifty percent of the diameter, so we can likewise say:

For a circle through a **radius** that **1**

The distance half way about the circle is **π = 3.14159265...**

## Digits

π is around equal to:

**3.14159265358979323846…**

The digits go on and also on v no pattern.

π has been calculation to end sixty sunshine decimal places and also still over there is **no pattern**to the digits

## Approximation

A quick and also easy approximation because that π is 22/7

22/7 = **3.1428571...**

But as you have the right to see, 22/7 is **not precisely right**. In reality π is no equal to the ratio of any two numbers, which makes it one irrational number.

A really good approximation, far better than 1 part in 10 million, is:

355/113 = **3.1415929...****(think "113355", slash the center "113/355", then flip "355/113")**

**Summary:**

22/7 | = | 3.1428571... |

355/113 | = | 3.1415929... |

π | = | 3.14159265... |

**Remembering The Digits**

**I usually simply remember "3.14159", but you can likewise count the letter of:**

**"May I have a huge container the butter today" 3 1 4 1 5 9 2 6 5**

**To 100 Decimal Places**

**To 100 Decimal Places**

**Here is π through the first 100 decimal places:**

### Calculating Pi Yourself

**There are countless special approaches used to calculation π and here is one you can shot yourself: that is referred to as the Nilakantha series** (after an Indian mathematician who lived in the years 1444–1544).

It walk on for ever and also has this pattern:

3 + *4***2×3×4** − *4***4×5×6** + *4***6×7×8** − *4***8×9×10** + ...

(Notice the + and also − pattern, and additionally the sample of numbers below the lines.)

It gives these results:

TermResult (to 12 decimals)

1 | 3 |

2 | 3.166666666667 |

3 | 3.133333333333 |

4 | 3.145238095238 |

... | ... Etc! ... See more: How Many Cm In 42 Inches ? Convert 42 Inches To Centimeters |

Get a calculator (or usage a spreadsheet) and also see if you have the right to get better results.

### Pi Day

Pi work is commemorated on march 14. March is the 3rd month, so the looks favor 3/14

Activity: uncover an Approximate worth For Pi

one Radians Annulus Irrational Number