SOURCE

<div class="wrapper">
  <div>1</div>
  <div>2</div>
  <div>3</div>
  <div>4</div>
  <div>5</div>
  <div>6</div>
</div>

.wrapper {
    display: grid;
    grid-template-columns: 100px 100px 100px;
    grid-template-rows: 50px 50px;
    grid-gap :10px;
}

div {
  font-size:30px;
  text-align:center;
  background-color:yellow;
}