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Symbol | Definition |
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≡ | exactly equal |
≈ | approximately equal to |
= | equal to |
digits | indicates that digits repeat infinitely (e.g. 8.294 369 corresponds to 8.294 369 369 369 369 …) |
A quad is a unit of energy equal to 1015 (a short-scale quadrillion) BTU, or 1.055 × 1018 joules (1.055 exajoules or EJ) in SI units.
The hartree (symbol: Eh or Ha), also known as the Hartree energy, is the atomic unit of energy, named after the British physicist Douglas Hartree.