Hands up: what is the biggest number you have ever seen written down? Think of numbers on signs, price tags, bills at home, or scoreboards. Some might be figures into the hundreds of thousands.

Watch four numbers slot into place-value columns. We start small and build up. Each number teaches us something a bit different. Before each one lands, read the column names out loud with me so we all hear what each column is called.

4,073: the placeholder zero

Four thousands, no hundreds, seven tens, three units. Notice how the zero in the hundreds column does an important job. It holds the column open. Take it away and the four slides into the wrong place — the 4 would only be worth 400, not 4,000. We read this as "four thousand and seventy-three" — we don’t say the zero out loud, but we still need it on the page.

9,999: nine in every column — as high as each column can go

Nine of each. What happens if we add one more? The thousands column fills up and tips one digit to the left into a brand-new column.

12,508: meeting ten-thousands

Now we need a new column on the left: TTh, ten-thousands. One ten-thousand, two thousands, five hundreds, no tens, eight units.

405,612: and hundred-thousands too

Six digits this time, with the HTh column (hundred-thousands) on the left. Four hundred thousand, no ten-thousands, five thousands, six hundreds, one ten, two units. Read it left to right and the comma helps you find your place.

Today the columns stretch all the way to hundred-thousands: HTh, TTh, Th, H, T, U. When a number is called out, one person comes up to the board to build it. While they build, everyone in their seat reads the columns silently and works out the finished number. Then we read the finished number back aloud. If a column looks off, we name the column we need to fix.

Today's bank: 3,072, then 70,309, then 105,008, then 800,070. We take turns at the board. While one pupil builds, everyone in their seat works out silently which zeros are doing the placeholder work. Before the builder taps Check, they say the placeholder zeros out loud. The class agrees or names any zero they missed. Then we read the whole number back aloud.

What we learnt today

• The same place-value frame works for any whole number, from units all the way to millions.
• Each column to the left is worth ten times the column on its right.
• Zero holds a column open. Without it, the other digits would slide into the wrong place.

Coming up