Subtract by Counting On - Up to 10
š¤ Here's a different way to subtract! Instead of counting back, we can count UP from the smaller number to the bigger number. This is a great strategy when numbers are close together!
Concept
"Subtract by Counting On" is like finding the distance between two numbers on a number line.It turns a subtraction problem into an addition puzzle! šÆ ** When to Use This Strategy:** This works best when the numbers are very close, like ** 9 - 7 **.Counting back 7 steps is a lot of work.Counting ON from 7 to 9 is super fast! ** Example: 9 - 7 = ?** 1. ** Re - phrase the question:** Instead of "9 take away 7," ask yourself, "How do I get from 7 to 9?" or "7 + what = 9?" 2. ** Start at the smaller number:** Start at 7. 3. ** Count On until you reach the bigger number:** Count up from 7 until you get to 9. * "8, 9" 4. ** Count your steps:** How many numbers did you say ? You said two numbers("8" and "9"), which means you took 2 steps. 5. ** The answer is 2! ** So, 9 - 7 = 2. It's like climbing a ladder from the 7th step to the 9th step. It only takes 2 more steps!
Try it
Let's practice finding the difference by counting on! **Instructions:** For each problem, count on from the smaller number to the bigger number to find the answer. **Problem 1: 8 - 6 = ?** * Think: "6 + what = 8?" * Start at 6 and count up to 8: "7, 8" * How many steps was that? ___ **Problem 2: 7 - 5 = ?** * Think: "5 + what = 7?" * Count on from 5: "___, ___" * Answer: ___ **Problem 3: 10 - 8 = ?** * Count on from 8 to 10. * Answer: ___ **Problem 4: 9 - 8 = ?** * This one is super fast! * Answer: ___ š **Strategy Choice:** For which of these problems would "Counting On" be the FASTEST strategy? Circle it. * A) 10 - 2 * B) 10 - 8 * Why did you choose that one?