Edit in JSFiddle

<div class="flex-container">
<div class="item order3">3</div>
<div class="item order2">2</div>
<div class="item order1">1</div>
<div class="item order-5">-5</div>
<div class="item">0</div>
<div class="item">0</div>
<div class="item order1">1</div>
</div>

.flex-container{
  display: flex;
flex-direction: row;
padding: 15px;
border: 1px solid #e2e2e2;
}
.item{
  background-color: #2da192;
  text-align: center;
  height: 100px;
  line-height: 100px;
  font-size: 30px;
  margin: 5px;
  font-weight: 600;
  color: #fff;
  width: 100px;
}
.order3{
  order: 3;
}
.order2{
  order: 2;
}
.order1{
  order: 1;
}
.order-5{
  order: -5;
}