Easily square numbers from 801 to 899.
Example
{% scaleimage l313_example.png %}
Step 1
Square the last 2 digits.
{% scaleimage l313_step1.png %}
Step 2
Multiply the last two digits by 16.
05 x 16 = 80
Step 3
Add two zeros to the end of step 2.
80 x 100 = 8000
Step 4
Add the results of step 1 and step 3.
8000 + 25 = 8025
Step 5
Add 640000 to the result of step 4.
640000 + 8025 = 648025
{% scaleimage lesson_underline.png %}