Bootstrap 4 carousel 3 multiple items Increment by 1 code example

Example: bootstrap 4 carousel multiple items responsive

<!-- Top content -->
<div class="top-content">
    <div class="container-fluid">
        <div id="carousel-example" class="carousel slide" data-ride="carousel">
            <div class="carousel-inner row w-100 mx-auto" role="listbox">
                <div class="carousel-item col-12 col-sm-6 col-md-4 col-lg-3 active">
                    <img src="assets/img/backgrounds/1.jpg" class="img-fluid mx-auto d-block" alt="img1">
                </div>
                <div class="carousel-item col-12 col-sm-6 col-md-4 col-lg-3">
                    <img src="assets/img/backgrounds/2.jpg" class="img-fluid mx-auto d-block" alt="img2">
                </div>
                <div class="carousel-item col-12 col-sm-6 col-md-4 col-lg-3">
                    <img src="assets/img/backgrounds/3.jpg" class="img-fluid mx-auto d-block" alt="img3">
                </div>
                <div class="carousel-item col-12 col-sm-6 col-md-4 col-lg-3">
                    <img src="assets/img/backgrounds/4.jpg" class="img-fluid mx-auto d-block" alt="img4">
                </div>
                <div class="carousel-item col-12 col-sm-6 col-md-4 col-lg-3">
                    <img src="assets/img/backgrounds/5.jpg" class="img-fluid mx-auto d-block" alt="img5">
                </div>
                <div class="carousel-item col-12 col-sm-6 col-md-4 col-lg-3">
                    <img src="assets/img/backgrounds/6.jpg" class="img-fluid mx-auto d-block" alt="img6">
                </div>
                <div class="carousel-item col-12 col-sm-6 col-md-4 col-lg-3">
                    <img src="assets/img/backgrounds/7.jpg" class="img-fluid mx-auto d-block" alt="img7">
                </div>
                <div class="carousel-item col-12 col-sm-6 col-md-4 col-lg-3">
                    <img src="assets/img/backgrounds/8.jpg" class="img-fluid mx-auto d-block" alt="img8">
                </div>
            </div>
            <a class="carousel-control-prev" href="#carousel-example" role="button" data-slide="prev">
                <span class="carousel-control-prev-icon" aria-hidden="true"></span>
                <span class="sr-only">Previous</span>
            </a>
            <a class="carousel-control-next" href="#carousel-example" role="button" data-slide="next">
                <span class="carousel-control-next-icon" aria-hidden="true"></span>
                <span class="sr-only">Next</span>
            </a>
        </div>
    </div>
</div>