Printable Mental Addition Worksheets
Printable mental addition worksheets for 2nd and 3rd grade, with an answer key on every sheet. The sets below cover 6 different skills, so you can start where your child actually is. Available as speed drills, word problems, and visual guides.
Targeted Practice by Skill
Add 1-digit to 2-digit mentally
Add 10 And 100
Add 1-digit to 2-digit mentally
Split The Ones
Add two 2-digit numbers mentally
Add 10 And 100
Add two 2-digit numbers mentally
Tens And Ones Split
Add 10, 100 and 1,000
Add 10 And 100
Add 10, 100 and 1,000
Addition Mental Addition 03
Add 10, 100 and 1,000
Add 10 100 1000
Add 10, 100 and 1,000
What Was Added
Add near tens, plus 9 and plus 19
Add 10 And 100
Add near tens, plus 9 and plus 19
Round And Adjust Rail
Add near tens, plus 9 and plus 19
Which Is Quicker
Compensation strategy
Add 10 And 100
Compensation strategy
Give And Take Seesaw
Compensation strategy
Make One Round
Estimate sums by rounding
Estimate Sums By Rounding
About Mental Addition
What this skill is
Mental addition develops strategies for adding numbers mentally without paper calculation, including breaking apart by place value (45 + 32 = 40+30 + 5+2 = 77) and compensation.
When children learn it
Mental addition strategies are taught in 2nd through 4th grade, aligned to 2.NBT.B.8 and 3.NBT.A.2.
Teaching Tips
- Add tens first, then add ones (for 34 + 25: 34 + 20 = 54, plus 5 = 59).
- Practice rounding to the nearest ten and compensating.
Common Mistakes
- Forgetting to adjust for compensation rounded numbers (like adding 30 instead of 29 without subtracting 1).
- Losing track of place value sums during mental steps.