Multiplication trick

Let me introduce you all to a different way of multiplication.
Suppose you want to multiply 401 with 25
Enter them in 2 columns -the smaller number 25 preferably in the first column
In the first column write down one by one values after dividing by 2(If there is a remainder ignore it ).
In the second column write down one by one values after multiplication by 2 ,corresponding to each entry in the first column.
Select values in first column which are odd numbers and write down the corresponding entries in the second column.Add these entries of the second column.The total  will be the required product.-See below the working-
25-------401
12...........802
6............1604
3............3208
1............6416
The odd numbers in the first column are 25,3and 1.The corresponding entries in the second column are 401,3208 and 6416.Add these you get 10025 which is the product of 25 and 401.
Another Example-27 to multiply with 48
27...........48
13...........96
6............192
3............384
1............768..The required product   48+96+384+768=1296.
You can also enter the bigger number in the first column but this will only result in more entries in each column..