Property	Description
Math.E	Returns Euler's constant, the base of natural logarithms. The E property is approximately equal to 2.718.
Math.LN10	Returns the natural logarithm of 10. The LN10 property is approximately equal to 2.302.
Math.LN2	Returns the natural logarithm of 2. The LN2 property is approximately equal to 0.693.
Math.LOG10E	Returns the base-10 logarithm of E, Euler's constant. The LOG10E property is approximately equal to 0.434.
Math.2E	Returns the base-2 logarithm of E, Euler's constant. The LOG2E property is approximately equal to 1.442.
Math.PI	Returns the ratio of the circumference of a circle to its diameter. The PI property is approximately equal to 3.14159.
Math.SQRT1_2	Returns he square root of 0.5, or one divided by the square root of 2. The SQRT1_2 property is approximately equal to 0.707.
Math.SQRT2	Returns the square root of 2. The SQRT2 property is approximately equal to 1.414.

The following function returns the area of a circle with a given radius:

function circle(r) {
  return Math.PI * r * r;
}

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