Hands up: what is the biggest number you have ever seen written down? A price in a shop window, the number of people at a match, the distance to the moon?

Call out a few and we will write them up on the board together. Some of these numbers are huge, but every one of them is built the same way, out of the same handful of columns you already know.

The interactive builds each number on a six-column place-value mat: HTh, TTh, Th, H, T and U. Every number today sits in this same mat, just filling more or fewer columns. Watch what the empty columns are doing.

We will use the same six-column mat we just saw, with the columns HTh, TTh, Th, H, T, U. Today we work through these numbers together: 3,072, then 70,309, then 105,008, then 800,070.

Now we build a fresh set on the mat, each one a little trickier than the last: 8,004, then 60,030, then 200,109, then 700,005.

What we did today

• We went back over our place-value columns, from hundred-thousands all the way down to units.
• We read, wrote and built numbers up to the hundred-thousands, watching how zeros hold a column open.
• We reminded ourselves that each column to the left is worth ten times the one on its right.