Max Rescues Birthday Balloons: Subtract by Tens!

About this Grade 1 Subtracting Multiples Of 10 Drill

Subtracting multiples of 10 is a foundational skill that helps first graders understand how our number system works in chunks rather than counting down one by one. When children can quickly calculate 35 - 10 or 50 - 20, they're building mental math fluency that makes all future subtraction easier and faster. This skill also develops number sense—the ability to see that removing a group of 10 doesn't change the ones place, only the tens place. At ages 6-7, students are developing abstract thinking, and working with tens helps them move away from counting on fingers toward recognizing patterns. Mastering this concept now creates confidence for two-digit subtraction later and shows children that math follows predictable rules they can discover themselves.

What your student will practice

• Subtract multiples of 10 from two-digit numbers using tens-place reasoning
• Recognize that subtracting 10, 20, or 30 changes only the tens digit
• Solve subtraction problems with multiples of 10 without counting by ones
• Apply tens subtraction to real-world scenarios and word problems

Common mistakes to watch for

The most common error is when students try to subtract multiples of 10 by counting backward one at a time instead of manipulating the tens place. You'll see this when a child solving 42 - 10 counts "41, 40, 39..." instead of recognizing the answer is 32. Another frequent mistake is confusing which digit changes—students might incorrectly alter the ones place instead of the tens place, turning 67 - 20 into 47 or 65. Watch for hesitation or finger-counting as signs the student hasn't grasped that tens subtraction is a pattern, not a counting task.