Subtract by Counting Back - Up to 20
🧠 Put away the number line, it's time to count back in your head! You can subtract small numbers quickly just by counting backward.
Do this: Read the concept below, then try the quiz or activity.
Concept
Once you are good at hopping on a number line, you can do those hops right inside your brain! This is called "counting back".
🎯 The "Count Back" Strategy: This works best when you are only subtracting a small number, like 1, 2, 3, or 4. Example: 17 - 3 = ? 1. Start with the big number: Say "17" out loud and put it in your head. 2. Hold up fingers for the small number: Hold up 3 fingers. 3. Count backward and put down a finger each time: Say "16" (put down 1), "15" (put down 1), "14" (put down the last finger). 4. The last number you said is the answer! So, 17 - 3 = 14.
If the number you are subtracting is really big (like 17 - 15), this strategy takes too long. But for small take-aways, it's perfect!
Try it
Time to count backward in your head!
Instructions: Start at the big number and count backward to find the answer.
Problem 1: 16 - 2 = ? * Start at 16. Count back 2: "___, ___" * Answer: ___
Problem 2: 19 - 4 = ? * Start at 19. Count back 4. * Answer: ___
Problem 3: 13 - 1 = ? * Answer: ___
Problem 4: 20 - 3 = ? * Answer: ___