Arithmetic - Basics 2

Thursday, April 27, 2006

Previously we worked on how to easily add large numbers, but what if numbers are to be subtracted? Same method won't work. We have to make minor modifications in our method for that. Actually its quite simple, lets sharpen our pencils and get ready for fun.

Say you want to add and subtract few numbers at same time, suppose 8565 - 329 + 952. We start from units place, same as in Addition method.

5 - 9 + 2 = - 2

Because the result is in negative we Borrow 1 from 10's place of a positive value. Suppose we borrow from 8565, we can even borrow from 452, because its positive too.

We can subtract the answer from 10, because we have borrowed 1 from a positive value (i.e 10 - 2 = 8).

....-1
8565 - 329 + 952 = ---8

Next we continue with the 10's place i.e 6(-1) - 2 + 5 = 8

....-1
8565 - 329 + 952 = --88

Next we continue with the 100's place i.e 5 - 3 + 9 = 11, so we write down the units place and carry over the rest of the digits on the left side of positive number and not on the negative number means we can carry the number on 8565 and 952 but not over 329. Remember how we used to add numbers by addition method? We never count higher than 10 in our running total, you can do the same here but then you have to remember how many times you have reached the limit of 10, and carry that count.

1..-1
8565 - 329 + 952 = -188

Next we continue with the 1000's place i.e 8 + 1 = 9, so the final answer will be

1..-1
8565 - 329 + 952 = 9188

So now you are equipped with all the necessary tools that will be required to do your basic calculations.

Auf wiedersehen.