Texas Math Models

Try “number line” or “4.5D”

Compatible numbers

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

swap in numbers that are friendly together: this works for all four operations addingmultiplying and dividing 4,3672,258 →→ 4,4002,300 + 6,700 hundreds are friendly to add 24 × 6→25 × 6 144 ÷ 6→150 ÷ 6 ≈ 150≈ 25 friendly with 6 · exact answers 144 and 24

How this one works

How

swap in numbers that are friendly with each other, then compute.

Best when

you are estimating a × or ÷ problem.

The same problem, other ways