Question

(x%2)≠0 what does this mean - i dont understand the symbols

this is the whole example - i am trying to teach my self sets :(

Example 2 − The set {1,3,5,7,9} is written as

B={x : 1≤ x <10 and (x%2)≠0} <- Means : x is 1 and less than 10

Answer 1

% is used in a lot of programming languages as the modulo operator.


`a\%b=c\iff a\equiv c\mod b`

which is to say, the remainder upon dividing
`a` by
`b` is
`c`.

When you divide any integer by 2, you can get either a remainder of 0 or 1. So in your example,
`x\%2\\eq0` refers to all numbers
`x` between 1 and 9 that are not perfectly divisible by 2. In other words,
`x\%2\\eq0` refers to those
`x` that are odd. (This assumes
`B` is a subset of the integers.)