MATH PUZZLE: Can you replace...
[4222] MATH PUZZLE: Can you replace... - MATH PUZZLE: Can you replace the question mark with a number? - #brainteasers #math #riddles - Correct Answers: 286 - The first user who solved this task is Thinh Ddh
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MATH PUZZLE: Can you replace...

MATH PUZZLE: Can you replace the question mark with a number?
Correct answers: 286
The first user who solved this task is Thinh Ddh.
#brainteasers #math #riddles
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Christmas sign of the times....

As a little boy climbed onto Santa's lap, Santa asked the usual, "And what would you like for Christmas?" The child stared at him open mouthed and horrified for a minute, then gasped, "Didn't you get my E-mail?"

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Ultrasonic alarm

In 1953, the first U.S. patent for a burglar alarm operated by ultrasonic sound was issued to Samuel Bagno of New York City (No. 2,655,645) on a system for movement detection in a confined space by intruders or fire. It was manufactured as the Alertronic and first sold in Jun 1950. A sound source produced waves of 19,000 hertz, a frequency too high for normal human hearing. An intruder could be detected by the alarm by a difference in frequency of the reflected waves from the moving body (the Doppler effect). The device would then sound an alarm.
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