Max Rescues Robot City: Subtraction with Borrowing

About this Grade 2 Subtraction With Borrowing Drill

Subtraction-with-borrowing (also called regrouping) is a critical milestone for second graders because it moves them beyond simple subtraction facts into two-digit problem-solving. At ages 7-8, children are developing the abstract thinking needed to understand that 10 ones can become 1 ten—a concept that feels almost like a magic trick at first. This skill opens the door to all future multi-digit math, from third-grade multiplication to handling money in real life. When your child can confidently borrow, they're building number sense and persistence; they learn that when a problem seems stuck, there's always a strategy to try. Mastering regrouping also builds confidence because students realize they can tackle problems that initially look too hard, much like how artificial intelligence learns to solve complex tasks by breaking them into smaller steps.

What your student will practice

• Recognize when borrowing is needed in two-digit subtraction problems
• Regroup tens into ones to complete the subtraction
• Apply borrowing strategy to solve 20–99 minus 1–99 problems
• Check subtraction answers using addition

Common mistakes to watch for

The most common error is forgetting to reduce the tens column after borrowing. For example, when solving 32 – 15, a student borrows to make the ones 12 – 5 = 7, but then calculates the tens as 3 – 1 = 2 instead of 2 – 1 = 1, arriving at 27 instead of 17. Another frequent mistake is borrowing when it's not needed—a child might regroup even when the top ones digit is already larger than the bottom ones digit. Watch for students who write messy numbers or cross out sloppily; this makes it hard for them to track which numbers have changed.