Texas Math Models

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Try “number line” or “4.5D”

Home / Rounding & Estimating: Six Ways

Compatible numbers

367 + 258 = 625 Grade 3

How this one works

How

swap both numbers for ones you can add in your head.

Best when

the rounded numbers are still awkward.

The same problem, other ways

Vertical number line
The halfway mark
The digit rule · the shortcut
Round both, then compute
Is it reasonable?

Practice this

There’s a one-page printable version of this chart on Teachers Pay Teachers.

See the printable (opens Teachers Pay Teachers in a new tab)

Created by a Texas educator and former assistant principal with 11 years in elementary schools.

Questions? Email me at info@texasmathmodels.com · Contact page

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Aligned with EngageNY / Eureka Math and Bluebonnet Learning K–5 Math strategies · original visuals & notes.

Printable sets are on Teachers Pay Teachers, published as CTG Learning.

Written for teachers and parents. No student accounts; nothing is collected about any student.

Read Spanish? Every page has a Spanish version, and it’s still a first draft. Help check it.

An independent resource. Not affiliated with, endorsed by, or connected to the Texas Education Agency, STAAR, Bluebonnet Learning, Great Minds or Eureka Math.