Max Rescues Lost Jellyfish Friends: Add by Tens!

About this Grade 1 Adding Multiples Of 10 Drill

Adding multiples of 10 is a cornerstone skill that helps six- and seven-year-olds recognize patterns in our number system and build confidence with larger numbers. When children learn that 20 + 30 = 50, they're discovering that the tens place follows the same addition rules as the ones place—a critical insight for understanding how numbers work. This skill directly supports their ability to add two-digit numbers fluently by Grade 2 and strengthens their mental math strategies. Mastering multiples of 10 also makes real-world math feel manageable: counting money, grouping objects into tens, and solving word problems all become clearer. At this age, students are naturally drawn to patterns and repetition, making this the perfect time to cement these connections. Regular practice with adding multiples of 10 builds automaticity, meaning your child can recall answers quickly without counting on their fingers every time.

What your student will practice

• Add two multiples of 10 within 100 using place value understanding
• Recognize the pattern that tens add like ones (2 + 3 = 5, so 20 + 30 = 50)
• Solve one-step word problems involving addition of multiples of 10
• Represent addition of multiples of 10 using mental math or quick sketches

Common mistakes to watch for

The most common error is students treating the tens digit and ones digit separately without understanding the relationship. For example, a child might say 20 + 30 = 50 by accident, then 40 + 50 = 80 correctly, but can't explain why—they're guessing rather than recognizing the pattern. Another frequent mistake is students reverting to counting by ones: "20... 21, 22, 23..." instead of counting by tens. You'll spot this when a worksheet takes much longer than expected or when your child counts on their fingers despite knowing their basic facts. Listen for whether they say "two tens plus three tens equals five tens" or if they're silent and uncertain.