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.
Sum of Unit Fractions (fractions) The ancient Egyptians only used fractions of the form 1=n  we call them unit fractions. All other fractions had to be represented as a sum of such unit fractions and, furthermore, all the unit fractions should be dierent from each other. They had a notation for 1=2. and 1=3 and 1=4, etc., but they did not have a notation that allowed them to directly.