Here is a sum: 4,200 + 2,900. Roughly how much do you think that is altogether? Not the exact answer, just a good guess in your head. Would it be nearer to 6,000, 7,000, or 8,000?

The number line shows a marker between two thousands. Look where the marker sits and decide which thousand it is nearer. The last one has no line, so we round in our heads instead.

Today we work through these numbers together on the line, rounding each to the nearest thousand: 2,300 → 5,500 → 8,900 → 4,050. The 5,500 lands exactly on a middle mark, so we will use our halfway rule and say each one aloud before we check.

Today's challenge bank builds up: round 2,400, then 5,500, then 8,900, and finally estimate 4,100 + 3,850 by rounding each number first. The last one puts rounding and adding together.