Calculate the number 399
NUMBERMANIA: Calculate the number 399 using numbers [4, 2, 7, 4, 22, 670] and basic arithmetic operations (+, -, *, /). Each of the numbers can be used only once.Correct answers: 2
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Illuminating gasIn 1875, inventor and scientist, Professor Thaddeus S.C. Lowe (1832-1913) patented a process for water gas production of "illuminating or heating gas." This gas making process fundamentally consists of the spraying of oil into water gas (blue gas) in a hot vessel for the purpose of increasing the calorific value of the gas. This carbureted water gas process was soon the most important manufactured gas in the United States of its time. He later invented a number of important and basic devices for use in atmospheric observation and metallurgical processing. Earlier, during the Civil War, he had created a military balloon force to spy on Confederate troops. |