Easy Trick to Subtract 9 (e.g., 18 − 9)
Trick idea:
Instead of subtracting 9 directly, make it easier by using 10.
Add 1 to the number you’re subtracting from (the minuend).
→ 18 + 1 = 19
Now subtract 9 from 19.
→ 19 − 9 = 10
Subtract the 1 you added earlier.
→ 10 − 1 = 9
✔ So 18 − 9 = 9 using this trick!
This works because 9 = 10 − 1, so adding 1 and later removing it makes mental subtraction easier. �
📌 Why It Works (Simple Explanation)
When you want to subtract 9, think of 9 as (10 − 1):
Instead of directly subtracting 9, subtract 10 (easy!)
Then add back 1 (because you subtracted one too many)
➡ That’s exactly what your steps do:
Add 1 → subtract 9
Equivalent to subtracting 10 then adding 1. �
Jagranjosh.com
✍️ Example way :-
Here’s a ready-to-paste explanation you can use:
Super Fast Trick to Subtract 9!
To solve 18 − 9 quickly in your mind:
1️⃣ Add 1 to 18 → 19
2️⃣ Subtract 9 → 10
3️⃣ Subtract 1 → 9
So, 18 − 9 = 9 🧠💡
(Why? Because 9 is just 10 − 1, so adding and removing 1 helps you calculate mentally without writing.) �
Jagranjosh.com
Comments
Post a Comment