How to Square A Number With Last Digit 5?
In my last post I have shown how to multiply with two numbers without using calculator. This is bit advanced post where I will show to make a square a number having five at last without using a calculator.
Say I have to square 15 that is 15X15=225
How to derive this my using simple calculation:
Divide the numbers in the below written manner:
|Format the number|
Draw a line just after 5
|Step-2 Draw a line just after 5|
Multiply 5*5=25 and write it to the right of the bar
|Witting first calculation|
Now add one to the top number here it is 1 so top number becomes 1+1=2
|Adding 1 to the top|
Multiply 2*1(that is the left hand side ..this can be done again with multiply two number method)
Hence the result has come to 225.
Now let us try with a big number called 95X95
As per Step-1 and 2 this will look like-
Following step -3 we will get 5*5=25
Following Step-4 we need to add 1 to the top that is 9 will become 9+1=10
As per the final step we need to multiply with 10*9 hence it becomes 90