Calculate the number 547
NUMBERMANIA: Calculate the number 547 using numbers [4, 9, 2, 5, 13, 130] and basic arithmetic operations (+, -, *, /). Each of the numbers can be used only once.Correct answers: 3
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Ozone layerIn 1987, the "Montreal Protocol on Substances that Deplete the Ozone Layer" was signed, agreeing that the production and consumption of most compounds that deplete ozone in the stratosphere, such as chlorofluorocarbons (CFCs), were to be phased out by 2000. It was further adjusted and amended at subsequent Meeting of the Parties between 1990 and 1997. Because of their relatively high ozone depletion potential, several man-made compounds in addition to (CFCs), carbon tetrachloride, methyl chloroform, and halons were targeted first for phaseout. Now, the U.S. Clean Air Act, for example, bans the release of ozone-depleting refrigerants the during maintenance or disposal of air conditioners and other refrigeration equipment. |