We will work three multiplications on the board, each in two parts: first a rounded estimate, then the real working row by row. Watch what happens to the second row each time, and keep an eye on where the real answer lands compared to the estimate.

Today we estimate first, then work it out, and check each result against the estimate. We'll do the written long multiplication together on the board, and use the screen only for the estimate check. Our products come from a GAA weekend: 245 × 32 (tickets for 32 matches), then 517 × 26, then 683 × 45. For each one we say the rounded estimate aloud before anyone touches the working, so we always know roughly where the answer should land. Remember what a place-value slip looks like: if the tens row lands one column too far right, the answer comes out much too small, so 517 × 26 giving 4,136 (far too small) would be a slipped row.

For each one we predict roughly how big the answer will be before we work it out on the board. The screen is just for the estimate; the long multiplication is written out by hand. If there is time, see whose estimate landed within five hundred of the real answer.