Сергей Ракипов,
если ещё изменить разметку, то код можно будет сократить.
<!DOCTYPE HTML>
<html>
<head>
<title>Untitled</title>
</head>
<body>
<style>
body {
font-family: monospace;
font-size: .8rem;
}
main {
max-width: 720px;
margin: 0 auto;
}
section {
max-width: 480px;
margin: 0px auto 0px;
}
.total_all {
margin: 40px 0px 40px 0px;
font-size: 2rem;
}
.summa {
margin: 40px 0px 0px 0px;
font-size: 1.2rem;
}
.number {
padding: 0px 0px 0px 20px;
}
.summa>.container {
margin-left: 20px;
}
.summa>.container input {
margin-left: 15px;
}
</style>
<body>
<section>
<div class="total_all"></div>
<div class="summa">
<label class="container">
<input type="checkbox" checked="checked">
<span class="checkmark"></span>
</label>
<div class="number">
<label class="container">2 000
<input type="checkbox" checked="checked">
<span class="checkmark"></span>
</label>
</div>
<div class="number">
<label class="container">2 000
<input type="checkbox" checked="checked">
<span class="checkmark"></span>
</label>
</div>
<div class="number">
<label class="container">2 000
<input type="checkbox" checked="checked">
<span class="checkmark"></span>
</label>
</div>
<div class="number">
<label class="container">2 000
<input type="checkbox" checked="checked">
<span class="checkmark"></span>
</label>
</div>
</div>
<div class="summa">
<label class="container">
<input type="checkbox" checked="checked">
<span class="checkmark"></span>
</label>
<div class="number">
<label class="container">2 000
<input type="checkbox" checked="checked">
<span class="checkmark"></span>
</label>
</div>
<div class="number">
<label class="container">2 000
<input type="checkbox" checked="checked">
<span class="checkmark"></span>
</label>
</div>
<div class="number">
<label class="container">2 000
<input type="checkbox" checked="checked">
<span class="checkmark"></span>
</label>
</div>
<div class="number">
<label class="container">2 000
<input type="checkbox" checked="checked">
<span class="checkmark"></span>
</label>
</div>
</div>
<div class="summa">
<label class="container">
<input type="checkbox" checked="checked">
<span class="checkmark"></span>
</label>
<div class="number">
<label class="container">2 000
<input type="checkbox" checked="checked">
<span class="checkmark"></span>
</label>
</div>
<div class="number">
<label class="container">2 000
<input type="checkbox" checked="checked">
<span class="checkmark"></span>
</label>
</div>
<div class="number">
<label class="container">2 000
<input type="checkbox" checked="checked">
<span class="checkmark"></span>
</label>
</div>
<div class="number">
<label class="container">2 000
<input type="checkbox" checked="checked">
<span class="checkmark"></span>
</label>
</div>
</div>
<div class="summa">
<label class="container">
<input type="checkbox" checked="checked">
<span class="checkmark"></span>
</label>
<div class="number">
<label class="container">2 000
<input type="checkbox" checked="checked">
<span class="checkmark"></span>
</label>
</div>
<div class="number">
<label class="container">2 000
<input type="checkbox" checked="checked">
<span class="checkmark"></span>
</label>
</div>
<div class="number">
<label class="container">2 000
<input type="checkbox" checked="checked">
<span class="checkmark"></span>
</label>
</div>
<div class="number">
<label class="container">2 000
<input type="checkbox" checked="checked">
<span class="checkmark"></span>
</label>
</div>
</div>
</section>
<script>
const section = document.querySelector('section');
const total = document.querySelector('.total_all');
const digits = n => n.toString().replace(/\B(?=(\d{3})+(?!\d))/g, " ")
section.addEventListener('change', function() {
let num = 0;
for (const div of document.querySelectorAll('.summa')) {
const checked = div.querySelector('input:first-child').checked;
let n = [...div.querySelectorAll('.number :checked')].reduce((n, {
previousSibling
}) => n + +previousSibling.data.replace(/\s/g, ''), 0)
for (const el of div.querySelector(':first-child').childNodes)
if (el.nodeType === 3) el.remove()
div.querySelector(':first-child').prepend(digits(n));
if (checked) num += n
}
total.textContent = digits(num);
})
let event = new Event("change");
section.dispatchEvent(event);
</script>
</body>
</body>
</html>