Max Rescues Lost Satellites: Add by Tens Mission!

About this Grade 2 Adding Multiples Of 10 Drill

Adding multiples of 10 is a foundational strategy that helps second graders see patterns in our number system and makes mental math feel manageable. When children grasp that 20 + 30 is really just 2 tens + 3 tens = 5 tens, they're building number sense and confidence with larger numbers. This skill directly supports their ability to add two-digit numbers without always relying on manipulatives or counting on their fingers. By age 7 or 8, students are developmentally ready to move beyond concrete counting and into thinking about groups or "bundles" of ten—the same way we might think about counting groups of satellites orbiting Earth rather than counting individual objects. Mastery here makes third-grade addition and subtraction feel less overwhelming. Most importantly, students who can fluently add multiples of 10 develop the mental math habits they'll use for the rest of their math lives.

What your student will practice

• Recognize and count by tens to build fluency with multiples of 10
• Add two multiples of 10 using tens-place thinking without regrouping
• Apply adding-multiples-of-10 to solve word problems with two-digit sums
• Explain or show how 30 + 50 relates to 3 tens + 5 tens

Common mistakes to watch for

Many second graders try to add the tens digits but forget they're working with tens, arriving at answers like 30 + 40 = 7 instead of 70. You'll spot this error if the child writes single-digit answers to multiples-of-10 problems. Another common trap is adding the zeros: students sometimes compute 30 + 40 as 3 + 4 + 0 + 0 = 7, then tack a zero on the end to get 70—they get the right answer for the wrong reason. Watch for children who revert to counting by ones or using fingers when the numbers get to 50, 60, or higher; this signals they haven't internalized the ten-ness of the problem.