Easily square numbers from 20 to 29.
Example
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Step 1
Square the ones place digit.
{% scaleimage l301_step1.png %}
Step 2
Multiply the ones place digit by 4.
4 x 6 = 24
Step 3
Add a zero to the end of step 2.
24 x 10 = 240
Step 4
Add the results of step 1 and step 3.
240 + 36 = 276
Step 5
Add 400 to the result of step 4.
276 + 400 = 676
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