Clinical signs are usually seen 3-5 days after exposure. Second-generation coumarins and indandiones are toxic with a single dose. Second-generation coumarins are a greater hazard than first-generation coumarins if the dog or cat eats a poisoned rat or mouse.
Quick Answer. Fractions were created by the ancient Egyptians in 1800 B.C. Egyptians created a number system on a base 10 concept, which is similar to the numerical systems used in the United States and around the world for creating fractions. Originally, Egyptians used pictures as well as numerals to display and differentiate numbers.
Pi, given its name after the Greek letter, was not named so by the Greeks, nor did they invent the concept. It is true that the Ancient Egyptians first discovered the number, and there are references to a number in an Egyptian scroll dating to 1650 BCE.rchimedes approximated it in about 200 BCE in fraction form, since the Greeks did not yet use decimals. He expressed pi as a fraction similar to 3 1/7, which is in decimals approximately 3.14. Mathematicians and scientists left pi at Archimedesâ calculation for centuries.