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About this Grade 1 Adding Multiples Of 10 Drill

Adding multiples of 10 is a cornerstone skill that helps first graders build number sense and mental math confidence. When children master 20 + 30 or 40 + 10, they're learning that we can work with groups of tens rather than counting individual ones—a huge leap in mathematical thinking. This skill directly supports their ability to add two-digit numbers later and makes real-world tasks like counting money or library books on shelves feel manageable rather than overwhelming. At ages 6 and 7, brains are developing the pattern-recognition abilities needed to see that 3 tens plus 4 tens equals 7 tens, not just a random number fact to memorize. Practicing these combinations strengthens the tens place understanding that underpins all future place-value work. This worksheet builds the automaticity children need so they can focus mental energy on more complex addition strategies as they progress.

What your student will practice

• Recognize and add two multiples of 10 mentally without counting by ones
• Understand that adding tens uses the same facts as adding single digits
• Apply multiple-of-10 addition to solve one-step word problems
• Write equations correctly when adding two multiples of 10

Common mistakes to watch for

Many Grade 1 students accidentally add the tens digits and then add a zero, producing answers like "50 + 30 = 80" written as "5 + 3 = 8, add a zero = 80"—which works but shows they're not yet thinking about the tens place conceptually. Others count by ones all the way, defeating the purpose of the strategy, or forget to regroup entirely and guess. Watch for students who write "5 + 4 = 9" when solving 50 + 40, suggesting they're ignoring the zeros. These errors signal the child still views tens and ones as separate concepts rather than as a unified place-value system.