This how-to video explains in detail about an alternate mental subtraction method.
This method is very simple if we practice this mentally rather than solving it on papers. Let's learn this method using an example, let us subtract 7589 from 9456, first we need to subtract 7000 from 9456, this will give us 2456, the reason for subtracting 7000 from 9456 is for simplifying the process, now what is 2456 and 589, so we have to subtract 589 from 2456, now let us subtract 500 from 2456 this will give us 1956,always remember the remaining numbers like 89 and 1956 which we need to subtract to get the final result. Now we have to subtract 89 from 1956, to do this let's subtract 80 from 1956, this will give us 1876, and the remaining numbers are 1876 and 9, and finally we have to subtract 9 from 1876, this will finally give us a result of 1867. The key facts to be considered in this process is that always remember the new number and the number that is left over. And since we are considering whole numbers this process makes the subtraction process a lot simpler especially during mental subtraction.
This method is very simpler than the normal paper method, since the subtraction process gets simpler as the process progresses, Hence those who needs mental subtraction for their work can really practice this method and can get benefited.