Texas Math Models

Try “number line” or “4.5D”

The halfway mark

4,367 + 2,258 = 6,625 Grade 4

the midpoint decides, and a number sitting exactly on it always rounds UP not yet at the midpointexactly on the midpoint 4,0005,000 4,500 4,367 4,367 has not reached 4,500, so it is nearer 4,000 4,367 ≈ 4,000 4,0005,000 4,500 4,500 4,500 sits exactly on the midpoint: round UP 4,500 ≈ 5,000 the same rule at any place: 250 ≈ 300, 4,350 ≈ 4,400

How this one works

How

find the halfway number, then see which side yours is on.

Best when

you forget which way to round.

The same problem, other ways