# Is Pi a real number?

Rupert Fulker asked, updated on February 15th, 2021; Topic: real numbers
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π is an irrational number, meaning that it cannot be written as the ratio of two integers. Fractions such as 22/7 and 355/113 are commonly used to approximate π, but no common fraction (ratio of whole numbers) can be its exact value.

Then, is the number 0 a real number?

Real numbers consist of zero (0), the positive and negative integers (-3, -1, 2, 4), and all the fractional and decimal values in between (0.4, 3.1415927, 1/2). Real numbers are divided into rational and irrational numbers.

Further to this, what is the Greek letter for Y?

Greek name of letterUpper Case SymbolPronunciation
GammaΓBetween Y as in yes and G as in go, but with no hard 'G' sound - more of a soft 'H' followed by the 'Y' sound in yes
DeltaΔTh as in the
EpsilonΕE as in very
ZetaΖZ as in zoo

No less, where does the phrase Not one iota come from?

An iota is something very small. An iota is the smallest letter of the Greek alphabet. The expression "not one iota" comes from the Bible (Matthew 5:18): "For truly, I say to you, until heaven and earth pass away, not an iota, not a dot, will pass from the Law until all is accomplished."

Why do engineers use j for imaginary numbers?

For example, in electrical engineering and control systems engineering, the imaginary unit is normally denoted by j instead of i, because i is commonly used to denote electric current. For the history of the imaginary unit, see Complex number § History.