Subtract 2-Digit Numbers using Number Lines
š¦ Hop in reverse! The giant frog is back, but this time it's taking huge -10 leaps backward towards zero.
Concept
When subtracting a big 2-digit number (like -23), we use our Giant Leaps and little Hops backward. šÆ **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: ___