Square root of 2 the square root of two, with a reasonable small denominator, the fraction (≈ 1.4142857) is sometimes used. The sequence in the OEIS gives the numerical value for the square root of two, truncated to 65 decimal places: The Babylonian clay tablet YBC 7289 (c. 1800–1600 BC) gives an approximation of in four sexagesimal figures, , which is accurate to about six decimal digits, and is the closest possible three-place sexagesimal representation of : Another early close approximation is given in ancient Indian mathematical texts, the Sulbasutras (c. 800–200 BC) as follows: "Increase the length [of the side] by its third
Square root of 2 widely used constant. formula_81 The (approximate) aspect ratio of paper sizes under ISO 216 (A4, A0, etc.) is 1:. This ratio of lengths of the shorter over the longer side guarantees that cutting a sheet in half along a line parallel to its shorter side results in the smaller sheets having the same (approximate) ratio as the original sheet. Proof: Let formula_82 shorter length and formula_83 longer length of the sides of a sheet of paper, with Let formula_85 be the analogue ratio of the halved sheet, then Square root of 2 The square root of 2, or the (1/2)th