# Useful Numbers

The most useful *irrational* numbers.

π = 3.14159...

pi

√2 = 1.414...

square root of 2

√3 = 1.732...

square root of 3

ɸ = 1.618...

phi

golden ratio

golden ratio

e = 2.718...

Euler's number

Napier's constant

Napier's constant

Memorize a few digits of each of these mathematical constants.

You will use π, √2, and √3 in simple geometry, ɸ and
e in higher mathematics.