Half Base - 50 . 500, 5000..

 Working Base - 50

In this blog we will find out how to extend all from 9 and last from 10 method to multiply numbers which are close to multiply or factor of 10,100, and so on

two sutra are used 

1. All from 9 and last from 10 - basic method 

2. proportionately - sub-sutra `  

Below Base 

Example:48 multiply by 46

50 =  100/ 2

          48 - 02                  

          46 - 04

         ----------

2)       44 / 08

---------------------

         22/08

Above the working base

Example 52 multiply by 56

 50 = 100/2

52   + 02

56   + 06

-------------

58    /  12

 29  /    12

58/2=29 

method is same but cross add instead of cross subtract. 

what happens when first part of the answer is odd ?

Example 44 multiply by 47

50 = 100/2

 

47  -  03 

44  -  06

-----------

41 /  18 

20 /  68

2) 4100 = 2050

4100 /2  = 2050 

50+18    = 68

44 multiply by 47 = 2068

Tip: you can use this same method for 500, 5000.. means half of the base only remember the base, depending upon the base you have to add the number in right hand side number