Subtract by Counting Back - Up to 20
š£ļø Time for a countdown! Counting back is the perfect way to quickly subtract small numbers without writing anything down.
Concept
If you are only subtracting 1, 2, 3, or 4 from a number, the fastest way to solve it is to just count backwards out loud! šÆ **The "Hold and Tap" Strategy:** **Example: 17 - 3 = ?** 1. **Hold the big number:** Say "17" out loud to lock it in your brain. 2. **Get your fingers ready:** Hold up 3 fingers for the number you are taking away. 3. **Tap and countdown:** Say the numbers backward as you tap your fingers down: "Sixteen, Fifteen, Fourteen." 4. **The last number is the answer!** So, **17 - 3 = 14**. If you try to count back a big number, like subtracting 12, it takes too long. But for small numbers, it's super fast!
Try it
Blast off with a countdown! **Instructions:** Start at the big number and count backward out loud. **Problem 1: 19 - 2 = ?** * Hold 19. Count back: "18, ___" * Answer: ___ **Problem 2: 15 - 4 = ?** * Hold 15. Count back 4 times. * Answer: ___ **Problem 3: 13 - 3 = ?** * Answer: ___ **Problem 4: 20 - 1 = ?** * (Just the number that comes right before it!) * Answer: ___