I) Let's square a two digit number that ends in 5. (without using your calculator :))
For example, we would like to square the number 65.
Step 1: Multiply the first digit of a number with the next number that comes after it. In this case 7 comes after 6.
6x7=42
Step 2: Now place 25 after it.
4225
Well, 65X65 = 4225
By the way, 5 is my favourite number. What's yours?
II) Let's square any two digit number.
For example 27.
Step 1: Look for the nearest ten boundary, which is 30 (27+3=30).
Step 2: Now go down 3 numbers from 27.
=24
Step 3: Multiply 24X30 = 720 (answer 1)
Step 4: 27 is 3 from nearest ten boundary 30
Now square of 3 = 9 (answer 2)
Step 5: Add (answer1) and (answer2)
720+9 = 729
27X27 = 729
