Max Rescues the Sand Castle: 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 base-ten number system works. When children learn that 35 − 10 = 25, they're not just memorizing facts—they're discovering that we can remove entire groups of ten without changing the ones place. This builds mental math speed and confidence, making larger subtraction problems feel manageable later on. At this age, children are developing number sense and learning to see numbers as made up of tens and ones, which is crucial for second-grade math. Mastering this skill also helps kids count backward by tens, a strategy they'll use for money, measurement, and telling time. When a child can quickly subtract 10, 20, or 30 from any number, they're building the flexible thinking that mathematicians rely on.

What your student will practice

• Subtract multiples of 10 from two-digit numbers with 90% accuracy
• Explain that subtracting 10 changes only the tens place, not ones
• Apply subtraction-by-tens strategies to solve word problems
• Count backward by tens from any starting number up to 100

Common mistakes to watch for

Many first graders mistakenly subtract 10 by taking away from the ones place instead of the tens place—for example, answering 43 − 10 = 33 instead of 33. Watch for students who count backward one-by-one instead of jumping by tens, which is slow and error-prone. Some children also confuse which digit changes; they might write 43 − 10 = 42, adjusting both places. You'll spot this pattern if a child hesitates or counts on fingers rather than recognizing the tens-place pattern immediately.