Max Conquers the Puzzle Palace: Add by Tens!

About this Grade 2 Adding Multiples Of 10 Drill

Adding multiples of 10 is a cornerstone skill that helps second graders build number sense and prepares them for two-digit addition with regrouping. When children grasp that 20 + 30 = 50, they're beginning to understand place value—recognizing that we can add tens just as easily as ones. This skill appears constantly in daily life: combining two groups of coins, calculating total points in games, or figuring out how many minutes until lunch (10 + 20 minutes). Mastering multiples of 10 also reduces cognitive load, so students can focus on harder addition problems later. At ages 7–8, children's brains are wired to spot patterns, making this the ideal window to cement the idea that 10 + 10 always equals 20, no matter the context. This foundation directly supports mental math strategies and confident problem-solving throughout third grade and beyond.

What your student will practice

• Fluently add two multiples of 10 within 100 using tens understanding
• Recognize and apply the pattern that 10 + 10 = 20, 30 + 20 = 50, etc.
• Translate word problems with multiples of 10 into addition sentences
• Use place-value thinking to verify and explain their own answers

Common mistakes to watch for

Many second graders accidentally add the tens digit and the ones digit separately, writing 20 + 30 as 2 + 3 = 5 (instead of 50). You'll spot this if a child writes answers like 5, 8, or 9 instead of 50, 80, or 90. Another common error is forgetting to write the zero in the ones place, so they'll write 5 instead of 50. Watch for students who line up the numbers incorrectly on paper, placing 20 under 30 in a way that mixes up place values. If you see these patterns, gently remind them that we're always adding tens, so the answer will always have a zero in the ones place.