I have divided the page 3 part and given 30% of width to every Image and the remaining 10% is divided by both sides of every Image that is 6 10%/6 sides. the answer is 1.6666 but the last image of every row isn't in the same row.
img{
width: 30%;
margin: 1.6666%;
}
<img src="http://unblast.com/wp-content/uploads/2021/08/Football-Vector-Illustration.jpg" alt="">
<img src="http://unblast.com/wp-content/uploads/2021/08/Football-Vector-Illustration.jpg" alt="">
<img src="http://unblast.com/wp-content/uploads/2021/08/Football-Vector-Illustration.jpg" alt="">
<img src="http://unblast.com/wp-content/uploads/2021/08/Football-Vector-Illustration.jpg" alt="">
<img src="http://unblast.com/wp-content/uploads/2021/08/Football-Vector-Illustration.jpg" alt="">
<img src="http://unblast.com/wp-content/uploads/2021/08/Football-Vector-Illustration.jpg" alt="">
<img src="http://unblast.com/wp-content/uploads/2021/08/Football-Vector-Illustration.jpg" alt="">
<img src="http://unblast.com/wp-content/uploads/2021/08/Football-Vector-Illustration.jpg" alt="">
<img src="http://unblast.com/wp-content/uploads/2021/08/Football-Vector-Illustration.jpg" alt="">
</body>