Home/Second Grade Math/Lesson 60
K-5 friendly lesson
One small step at a time.Read the idea, try the activity, and celebrate each win as you go.

Subtract 2-Digit Numbers using Number Lines

🦘 Hop in reverse! The giant frog is back, but this time it's taking huge -10 leaps backward towards zero.

Do this: Read the concept below, then try the quiz or activity.

Lesson 60 of 186

Concept

When subtracting a big 2-digit number (like -23), we use our Giant Leaps and little Hops backward.

🎯 The "Jump and Hop Backward" Strategy: Example: 65 - 23 = ? Instead of hopping backward 23 tiny times, break it up.

1. Start dot: Put your dot on 65.
2. Take Giant -10 Leaps: 23 has 2 tens. Take TWO leaps backwards!
   * Leap -10 backwards to 55.
   * Leap -10 backwards to 45.
3. Take Little -1 Hops: 23 has 3 ones. Take THREE hops backwards!
   * Hop -1 to 44.
   * Hop -1 to 43.
   * Hop -1 to 42.
4. You landed on 42.
So, 65 - 23 = 42.

Try it

Leap in reverse!

Instructions: Imagine the number line. Take negative leaps of 10, then negative hops of 1!

Problem 1: 58 - 34 = ? * Start at 58. * Take THREE -10 leaps backwards: 58 -> 48 -> 38 -> ___ * Take FOUR -1 hops backwards: 28 -> 27 -> 26 -> 25 -> ___ * Answer: ___

Problem 2: 76 - 21 = ? * Start at 76. * Take TWO -10 leaps backward: ___ * Take ONE -1 hop backward: ___ * Answer: ___

Problem 3: 49 - 15 = ? * Answer: ___

Problem 4: 93 - 42 = ? * Answer: ___

Complete & Continue β†’