Take the first digit and multiply it by the "next" number up. 65 x 65 The end is 25 . The first digit is 6. The next number up is 7. Put them together: 4,225 . How to Make it "Irresistible"
This is arguably the coolest-looking trick in mental math. It works for any two-digit number multiplied by 11. Mental Math Kids Can't Resist!: Tips, Short-cut...
It feels like a shortcut that lets them avoid the "old-fashioned" way. 2. Multiplying by 11: The "Split and Sandwich" Take the first digit and multiply it by the "next" number up
If the middle sum is 10 or more (like 87 x 11), just carry the "1" to the first digit! 3. The "Doubling and Halving" Method The next number up is 7
This is a lifesaver for multiplication tables that haven't been memorized yet. It simplifies complex problems into manageable ones.
At a restaurant, ask them to mentally calculate the 10% or 20% tip before you look at the receipt.