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A mathematical constant is a key number whose value is fixed by an unambiguous definition, often referred to by a symbol (e.g., an alphabet letter), or by mathematicians' names to facilitate using it across multiple mathematical problems. [1]
A decametre (International spelling as used by the International Bureau of Weights and Measures and by most English speaking countries, [1] [2] United States spelling dekameter or decameter [3] [4]), symbol dam ("da" for the SI prefix deca-, [1] "m" for the SI unit metre), is a unit of length in the International System of Units (SI) equal to ten metres.
Length; system unit code (other) symbol or abbrev. notes conversion factor/m combinations SI: gigametre: Gm Gm US spelling: gigameter 1.0 Gm (620,000 mi) megametre: Mm Mm US spelling: megameter
19 cm = 1.9 dm – length of a banana; 26.3 cm = 2.6 dm – length of average male human foot; 29.98 cm = 2.998 dm – distance light in vacuum travels in one nanosecond; 30 cm = 3.0 dm – maximum leg length of a Goliath birdeater; 31 cm = 3.1 dm – wingspan of largest butterfly species Ornithoptera alexandrae
When truncating, a number of this order of magnitude is between 10 6 and 10 7. In a similar example, with the phrase "seven-figure income", the order of magnitude is the number of figures minus one, so it is very easily determined without a calculator to be 6. An order of magnitude is an approximate position on a logarithmic scale.
Conversion of units is the conversion of the unit of measurement in which a quantity is expressed, typically through a multiplicative conversion factor that changes the unit without changing the quantity. This is also often loosely taken to include replacement of a quantity with a corresponding quantity that describes the same physical property.
First-order means that only the first derivative of y appears in the equation, and higher derivatives are absent. Without loss of generality to higher-order systems, we restrict ourselves to first-order differential equations, because a higher-order ODE can be converted into a larger system of first-order equations by introducing extra variables.
The base units are defined in terms of the defining constants. For example, the kilogram is defined by taking the Planck constant h to be 6.626 070 15 × 10 −34 J⋅s, giving the expression in terms of the defining constants [1]: 131 1 kg = (299 792 458) 2 / (6.626 070 15 × 10 −34)(9 192 631 770) h Δν Cs / c 2 .