Replace the question mark with a numberMATH PUZZLE: Can you replace the question mark with a number?
Correct answers: 144
The first user who solved this task is Vladimir Krnac.
#brainteasers #math #riddles
Lewis UrryDied 19 Oct 2004 at age 77 (born 29 Jan 1927).Lewis Frederick Urry was a Canadian-American chemical engineer who invented the ubiquitous alkaline batteries and, later, lithium batteries. After a few years working in Canada for the company that made Eveready batteries, he was transferred in 1955 to its Cleveland, Ohio, laboratory where he began work on a new battery with better life-span than the carbon-zinc type of the time. He succeeded by using manganese dioxide, an alkaline electrolyte and powdered zinc (which he realized had greater surface area than solid zinc). A patent was filed 9 Oct 1957, issued 15 Nov 1960, No. 2,960,558. Production began in 1959. Alkaline batteries are estimated to be 80% of all dry cell batteries now sold in the world. The Smithsonian Institution displays his prototype alkaline battery. Urry held over 50 patents.«