Book 7
DEFINITIONS.
1
1
An unit is that by virtue of which each of the things that exist is called one.
2
2
A number is a multitude composed of units.
3
3
A number is a part of a number, the less of the greater, when it measures the greater;
4
4
but parts when it does not measure it.
5
5
The greater number is a multiple of the less when it is measured by the less.
6
6
An even number is that which is divisible into two equal parts.
7
7
An odd number is that which is not divisible into two equal parts, or that which differs by an unit from an even number.
8
8
An even-times even number is that which is measured by an even number according to an even number.
9
9
An even-times odd number is that which is measured by an even number according to an odd number.
10
