Search results
Results from the WOW.Com Content Network
The kilogram, symbol kg, is the SI unit of mass. It is defined by taking the fixed numerical value of the Planck constant h to be 6.626 070 15 × 10 −34 when expressed in the unit J⋅s, which is equal to kg⋅m 2 ⋅s −1, where the metre and the second are defined in terms of c and Δν Cs. —
A Logarex system Darmstadt slide rule with 7 and 6 on A and B scales, and square roots of 6 and of 7 on C and D scales, which can be read as slightly less than 2.45 and somewhat more than 2.64, respectively. The square root of 7 is the positive real number that, when multiplied by itself, gives the prime number 7.
The SI has special names for 22 of these coherent derived units (for example, hertz, the SI unit of measurement of frequency), but the rest merely reflect their derivation: for example, the square metre (m 2), the SI derived unit of area; and the kilogram per cubic metre (kg/m 3 or kg⋅m −3), the SI derived unit of density.
7 is the only number D for which the equation 2 n − D = x 2 has more than two solutions for n and x natural. In particular, the equation 2 n − 7 = x 2 is known as the Ramanujan–Nagell equation . 7 is one of seven numbers in the positive definite quadratic integer matrix representative of all odd numbers: {1, 3, 5, 7, 11, 15, 33}.
The radical of any integer is the largest square-free divisor of and so also described as the square-free kernel of . [2] There is no known polynomial-time algorithm for computing the square-free part of an integer.
[1] [7] [8] According to this account, at the end of Hồng Bàng dynasty, there was a kingdom called Nam Cương (lit. "southern border") in modern-day Cao Bằng and Guangxi. [1] This was a confederation of 10 mườngs, in which the King resided in the central one (present-day Cao Bằng Province). The other nine regions were under the ...