JSFiddle - React, Tailwind, and code Playground
HTML
<span class='pups'>100</span>
<span class='pups'>200</span>
<span class='pups'>300</span>
<span class='pups'>3300</span>
<span class='pups'>9993300</span>
CSS
span {
display: block;
}
JavaScript
$('.pups').each(function() {
this.innerHTML = (parseInt(this.textContent) * 10)
.toString()
.split('')
.reverse()
.map((char, i) => char + (i % 3 ? '' : ' '))
.reverse()
.join('')
})