Max Rescues Lost Balloons: Adding Multiples of 10!

About this Grade 2 Adding Multiples Of 10 Drill

Adding multiples of 10 is a foundational skill that helps second graders recognize patterns in our number system and builds mental math fluency they'll use throughout elementary math. When children understand that 20 + 30 is really "2 tens plus 3 tens equals 5 tens," they're developing number sense that makes larger addition problems feel manageable. This skill directly supports place value understanding—a core concept in Common Core—and trains students to think about numbers in groups rather than as individual units. By age 7 or 8, children's brains are ready to see these patterns, and mastering multiples of 10 gives them confidence and speed in calculations. The ability to quickly add 40 + 50 or 20 + 20 reduces reliance on counting and frees up mental energy for more complex math thinking, much like a hot-air-balloon rises smoothly once it catches the right current.

What your student will practice

• Fluently add two multiples of 10 up to 100 without counting on fingers
• Recognize that adding multiples of 10 follows the same pattern as adding single digits
• Apply adding-multiples-of-10 to real-world word problems with two-digit totals
• Explain their thinking aloud using tens language (e.g., '3 tens plus 4 tens')

Common mistakes to watch for

Many second graders add the digits in the tens place but forget the zero, writing "7" instead of "70" when solving 30 + 40. Others revert to counting by ones instead of recognizing the tens pattern, laboriously counting from 30 to 70 on their fingers rather than seeing 3 tens + 4 tens = 7 tens. Some students also struggle when zero appears in the ones place, treating "20 + 10" differently than "2 + 1" even though the structure is identical. Watch for hesitation or finger-counting on problems with multiples of 10—this signals the child hasn't internalized the tens pattern yet and needs more concrete practice.