Mental Addition Trick -Learn Within 5 Minutes

Mental Addition Trick- learn within 5 minutes. Addition of any size numbers.

 In this short article you are going to learn mental addition trick for any size of numbers whether large or small.Average time to read within 5 minutes.I suppose here that you already know the normal process of addition.

Don’t use pen & paper.Once you learn it addition of numbers  will become fun for you.

Before we move to addition of bigger numbers ,first  learn mental addition trick for small numbers.

Example 12+45

12+45= 10+40+2+5=50+7=57

12 consists of 10 and 2
45 consists of 40 and 5
10+40=50
2+5=7
50+7=57

Notice that I have separated multiple of 10 from each of 12 and 45 and then added together.It will be easy to add multiple of 10 mentally.

Take another example 684+29.

684+29=Six hundred+ Eighty four + Twenty nine

600+ 80+20+4+9=600+100+13=700+13=713

43+76=40+70+3+6=110+9=119

Notice the way we are taking part of  numbers and adding together.

Now it is time for mental addition trick for large numbers.Suppose we take two big numbers  as 2512345 and 45698

At the first step we can assume there won’t be any carry over to change 25 .However, we can easily decide here just by looking that 25 won’t be changed.

So think on 12345 +45698.

Now 12345=12 thousand, 3 hundred, forty five

45698= 45 thousand, six hundred and ninety eight

12 thousand +45 thousand= 57 thousand

3 hundred plus 6 hundred= 9 hundred

Forty five plus ninety eight= 40+5+90+8=130+5+8=130+13=143

Result= 57 thousand, 9 hundred and 143= 57 thousand, 10 hundred and 43= 58 thousand and 43

Hence 2 512345+45698=25,58043.

Take another big numbers 4285923+ 6899.

4280000 +5923+6899

5 thousand +6 thousand=11 thousand

9 hundred+8 hundred=17 hundred= 1 thousand and 7 hundred

23+99=20+90+3+9=110+12=1 hundred and 22

So result of 5923+6899= 12 thousand+8 hundred+22=12822

Method of manipulation for mental addition

34+68 , to add this first learn golden rule

Golden rule 1 for Mental Addition.

In an expression of the form A+B , you add any number to A and subtract the same number from B, the value of expression won’t change. Similarly you can subtract from A and add to B and value of A+B won’t change.

Like in 34+68= 34-2 + 68+2 = 32+70=102

Other example: 69+23= 69+1 + 23-1= 70+22=92

Golden Rule 2 for Mental Addition.

This is based on manipulating both the numbers A & B in A+B to nearby integers and then compensating in last.

Take one other example 23+69

20+70=90
23-3=20
69+1=70
-3+1=-2, meaning of minus 2 here is that we get 2 less then original value. So to compensate we add 2 in the result.
90+2=92
We subtracted 3 from 23 and added 1 to 69 so to compensate it we do reverse of it in the answer 90 i.e add  3 subtract 1 =add 2

Another Example:

81+38
81-1=80

38+2=40
80+40=120

-1+2=+1 , meaning of plus 1 here is we get 1 more than original value so to compensate we subtract 1

Net result=120-1=119

Method of manipulating for large numbers.

5923+6899=6000-77+6900-1=6000+6900-78

Add 6 000 and 6900 as explained above, 6000+6000+900=12900.

So result= 12900-78= 12922-100(we added 22 in both the terms the expression value won’t change)=12822

We will explain this process in more details in  How to subtract numbers mentally at super fast speed.

You won’t be benefited in terms of speed if you don’t practice it mentally . Try to practice as much as possible to make it natural to you

So, by manipulating numbers to nearby  numbers you can calculate addition easily. Also try to think in terms of words or money while adding mentally.Like if you add 134+45 think it as $134+$45= $100+$30+$4+$40+$5=$170+9=$179.

Okay! Now can you apply your newly learnt mental addition trick ?.Try to solve these examples in your head as fast as possible.

Examples: 17+68 , 45+90,12+33, 106+67, 119+238, 4356+478,  5671+9812 , 122+564+234 , 98456+34562 , 124689+57389 , 4528950+489000+34257 etc.

Like & Share with friends:
Share
Niraj Tulsyan

Btech in Electronics & Communication.I love Maths, Science & Technology.