Curriculum placement
Grade 1. This describes the skill, not a learner estimate.
Adding three numbers
Combine three quantities using useful grouping
Problem types
- Combine three groups
- Find the two that make ten
- Write the make-ten step
Builds on
- Adding within 20
- Addition and subtraction facts within 5 · Useful idea
Adding three small numbers combines facts already known: add two first, then the third.
Leads to
- Adding several two-digit numbers · Extend the idea
Adding three numbers in any grouping extends to adding several numbers in convenient groups.
- Perimeter of a polygon · See it applied
The distance around a shape is the sum of its side lengths, so a triangle needs three addends.
- Mean of a data set · See it applied
The mean begins by adding all the data values, which is adding more than two addends.
Related skills
- Properties of addition and multiplication · Related idea
Adding three numbers in a different grouping gives the same total, which is the associative idea behind regrouping any product or sum.
- Add two-digit numbers · Shared foundations
- Equations for addition and subtraction stories · Shared foundations
- Counting on and counting back · Shared foundations
- The meaning of the equal sign · Shared foundations
Open the interactive map to explore lessons and skill connections.