Friendly Sums Answer Key
About This Worksheet
Friendly Sums is a third grade mental-math activity that shows students how the Associative Property can make addition easier. Each problem gives three addends that can be regrouped to create a friendly number such as 10, 20, 30, or another easy total. Students rewrite the grouping first, then find the sum. For example, (30 + 7) + 3 can be regrouped as 30 + (7 + 3), making the last two numbers equal 10. This helps children see that addition properties are useful tools for efficient computation.
Curriculum and Grade Alignment
This worksheet is intended for third grade learners who are ready to apply the Associative Property as a mental-math strategy. The main goal is to help students recognize pairs of addends that can be regrouped to make easier sums. Before beginning, your child should understand how grouping can change without changing the total. The next step is choosing efficient regroupings independently when solving larger addition problems. This activity supports mental math, number sense, flexible addition, and strategic use of properties.
Student Tasks
Students will solve ten addition problems with three addends. They first regroup the numbers to create an easier sum and then calculate the total. Examples include (30 + 7) + 3, (40 + 6) + 4, (70 + 5) + 5, and (25 + 5) + 15. The problems are designed so one pair of addends can make a friendly benchmark number. This builds efficient computation and recognition of useful number combinations.
Common Challenges and Misconceptions
Some students may add from left to right without noticing the easier grouping. Others may change the order of the numbers when the task is meant to emphasize regrouping. A child may also create a new grouping but still choose numbers that are not especially helpful. Encourage your child to look for pairs that make 10, 20, or another round number. Asking, “Which two numbers are easiest to add first?” can guide the strategy.
Implementation Guidance
Teachers can use this worksheet after introducing the Associative Property conceptually. It works especially well as a bridge from property vocabulary to practical mental math. Parents can ask the child to circle the two addends that make the friendliest sum before rewriting. After solving, compare the regrouped method with straightforward left-to-right addition. This helps students see why the property is useful.
Details and Features
This worksheet includes ten three-addend problems in a blue two-column grid. Each problem provides space for a regrouped expression and the final sum. A worked example at the top models how to regroup to make an easy total first. The printable supports the Associative Property, mental addition, number sense, and efficient strategy use.