We cannot take half of 9 people. The even numbers, then, are the numbers divisible by 2: 2, 4, 6, 8, and so on. The odd numbers are 1, 3, 5, 7, and so on. If you do not know half of some even number, you can find it by decomposing it mentally into two even numbers whose half you do know.
To draw a shape, line or angle accurately using a compass and straightedge (ruler). Sometimes you are also allowed to use a protractor and triangle.
Definition of construct. transitive verb. 1 : to make or form by combining or arranging parts or elements : build construct a bridge; also : contrive, devise construct a plan. 2 : to draw (a geometrical figure) with suitable instruments and under specified conditions Construct a regular hexagon with sides 3 inches long.