Max Conquers the Gold Rush: Add Multiples of 10!

About this Grade 2 Adding Multiples Of 10 Drill

Adding multiples of 10 is a cornerstone skill that helps second graders build mental math flexibility and number sense. When children can quickly add 20 + 30 or 40 + 50, they're learning to work with tens as units rather than counting by ones—a major cognitive leap at age 7 and 8. This skill transfers directly to real-world situations: calculating the total cost of two items at a store, combining groups of coins, or even tracking scores in games. Mastering multiples of 10 also prepares students for two-digit addition with regrouping and lays groundwork for multiplication and place value understanding later. During the Gold Rush era, traders needed to quickly add bags of gold dust worth 10, 20, or 50 ounces—the same mental math your child is building today. When students recognize that 30 + 20 follows the same logic as 3 + 2, they've unlocked a strategy that makes arithmetic faster and more confident.

What your student will practice

• Mentally add two multiples of 10 within 100 without counting by ones
• Recognize that adding tens is like adding ones in the tens place
• Use place value understanding to solve addition problems with multiples of 10
• Apply adding-multiples-of-10 to solve word problems with real quantities

Common mistakes to watch for

The most common error is that second graders count by ones instead of recognizing the tens pattern. For example, a child might solve 30 + 20 by counting "31, 32, 33..." rather than thinking "3 tens plus 2 tens equals 5 tens." Another frequent mistake is writing the wrong digit in the tens place—answering 30 + 40 = 7 instead of 70, because they only added the first digits without considering place value. You'll spot these errors when the child takes much longer than expected or writes answers that jump by ones. The fix is to use physical tens (bundles of ten sticks, blocks, or coins) alongside the numbers so the child sees 3 groups of 10 joining 4 groups of 10.