Convert diameter to circumference

Answer 1

The circumference of a circle is a little more than 3 times the diameter, so for a rough, approximate conversion, multiply the diameter by 3.

For a better conversion, multiply the diameter by π instead. π is a the Greek letter whose name sounds like 'pie'. It is often written 'pi' instead of π. π cannot be written down absolutely accurately, but you can make your conversion more and more accurate by using more and more accurate values for π.

Here are some values for π in order of increasing accuracy,

3.1

3.14

3.142

3.1416

3.14159

3.141593

(This list can go on forever.)

Answer 2

divide circumference by PI (3.14159...) to get diameter