Faster Maths – Addition Tricks
Addition is something that we’re doing right from the primary school. It’s extremely difficult to learn new techniques overnight; specially when we have to learn tricks about a whole bunch of topics. And that’s the reason I am going to show you a technique that will help you in adding faster with what you’ve already learned.
The reason, like I’ve already told, is it’s easy to learn a trick that utilizes your already existing stronger points. Answer me this: how many people can add single digit numbers fast? Almost anyone. Example: 3+4+2+1. This is extremely easy to calculate. How many can calculate two digit numbers fast? 17+4+7+2+6. Now this raises eyebrows of some students. How about 67+4+2+7+4?
Conclusion: Everyone is fast in counting when the numbers adds upto something below 10. Now how to utilizes this? Let see.
Extremely important: In dots addition, dot represents a ‘carry over’. In conventional addition, we add up everything, and then ‘carry over’ in the end. For example, in the addition below, 5+5+7+8 =25 is done and carry on (2) is done during the result.
1 4 5
However, in dots method, carry on is done whenever 10 is reached in a calculation. In other words, dots represent a ‘carry over. Simultaneously, the addition thus arrived at, is deducted by 10. So, if the result is exactly 10, the remainder is 0 (10-10). If the added number is 13, the remainder in 3. This remainder is then used in the next addition.
1 4 5
Here: In the first stage we added unit’s line. 5+5=10. Since the result is exactly 10, the remainder is 0 i.e (10-10=0). So, put a dot and start next addition 7+8=15. Now this time remainder is 5 (15-10=5). So put a dot and place 5 in results place.These two dots show the number to be carry on in tens place. Two dots means 2 is to be carried on. Five dots mean 5 is to be carried on.
In second stage we add 2+4+3+ (2dots of previous calc)=11. So, we place a dot and carry on remainder 1. Moving on with the calculation we write 1+3 = 4
In third stage, there is no number. So we just look at the carry on dots of previous calculation. Since there is one dot, we write 1.
Now lets see another example.
In the third stage we calculate hundred’s digits. 5+1+2+ (2dots in previous cal) = 10. So place a dot and move on to the next calculation.2+9=11. Here the remainder is 1. Put a dot and start the next addition with the remainder. 1+4 =5. Put 5 in the result and move on to the thousandth digits.
In forth stage, there is no number. So just see the number of dots in previous calculation and write 2 in the result.
Now you might ask why this particular way of adding. What’s the use?
Well there are two.
- You are adding up all digits to a total of 10. So faster speed and lesser chances of error
- Conventional methods or other shortcut tricks become increasingly difficult when the numbers are four or five digits. Three digits addition is rarely seen in IBPS.
However, you should do whatever you feel you are fast at. If you think you are faster the conventional way, then by all means stick to it. If you are a fast learner, you can try jumping by 10 techniques, too.