You may define two variables: number of repetitions and number of px to jump in each repetition. Something like this:
$numRepetitions: 3;
$pxJump: 10;
@for $i from 1 through $numRepetitions {
.h-space-top-#{$i * $pxJump} {
margin-top:#{$i * $pxJump}px
}
}
The output for that case would be the code you need:
.h-space-top-10 {
margin-top: 10px;
}
.h-space-top-20 {
margin-top: 20px;
}
.h-space-top-30 {
margin-top: 30px;
}
However, if you need for example to iterate 4 times and summing 5px in each jump you just need to change the value of the variables, like this:
$numRepetitions: 4; //4 instead of 3 repetitions
$pxJump: 5; //5px instead of 10px
@for $i from 1 through $numRepetitions {
.h-space-top-#{$i * $pxJump} {
margin-top:#{$i * $pxJump}px
}
}
In that case you'll get this code:
.h-space-top-5 {
margin-top: 5px;
}
.h-space-top-10 {
margin-top: 10px;
}
.h-space-top-15 {
margin-top: 15px;
}
.h-space-top-20 {
margin-top: 20px;
}