We then invented a new number indicated by the letter i with the property that i 2 = -1. This number does not fit on the Euclidean line where the real numbers have accommodated leaving no room for any other numbers. Mathematicians satisfied the desire to geometrically represent the multiples of i by choosing a Euclidean plane, with a straight line to represent the reals and the perpendicular line that goes through zero to represent the pure imaginary.

The effective rate is when the period of formation and incorporation of interest on capital coincides with that to which the rate refers. Some examples: - 140% per month with monthly capitalization. - 250% per semester with semiannual capitalization. - 1250% per annum with annual capitalization. The effective word, according to the dictionary, means real, true.

The World of Cubes There are eight distinct ways of grouping four cubes. Back to statement Challenge 184 Painting the faces of a cube Challenge table of contents Next >> Challenge 186 Investigating the sequel

ICOSAEDRO - A polyhedron with 20 faces. IDENTITY - Way of showing that two expressions have the same value. Odd - The integer is said to be not divisible by 2 or what has no 2 as a factor. TILT OF A STRAIGHT - If two points on a line have the same abscissa, the line is said to be vertical and if the abscissa is different the line is slanted.

The French physicist Joseph Louis Lagrange was born on January 25, 1736 and died on April 10, 1813. He was one of the most important mathematical and physical scientists of the late 18th century. He invented and brought about the calculus of variations and then applied them. the new discipline for CELESTIAL MECHANICS, especially for finding improved solutions to the THREE-BODY PROBLEM.

Georg Ferdinand Ludwig Philipp Singer was born on March 3, 1845 in St.Petesburg, Russia, and died on January 6, 1918 in Halle, Germany. He founded set theory and introduced the concept of infinite numbers with his discovery of cardinal numbers. He also advanced the study of trigonometric series.