PHP if is a multiple of an integer

Question

Within a for loop, i need to add some HTML that outputs only when the loop is on a [(multiple of 3) minus 1].

For example, what i could do is:

for($i=0;          


        

Answer 1

if(($i+1)%3 == 0){
    //do something
}

The % operator is known as the modulus operator and returns the remainder of a division.