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.
3. Something, such as a long grammatical construction, that is intricate or complex. 4. Mathematics An operation, such as negation, which, when applied to itself, returns the original number. 5. Embryology The ingrowth and curling inward of a group of cells, as in the formation of a gastrula from a blastula.