Welcome To DAY 6

I hope you felt proud yesterday after solving the test and are much more confident right now. Maths is simple, isn't it?

Basic Multiplication But Mentally and Faster.
The reason we are learning this method is because it is not possible to do all calculation using the add and subtract method. There are many other methods involved but this is simple and easy.
Rules: This method simplifies our normal method of multiplication. Just remember the following diagram when you multiplying 2 digit number with a 2 digit number.
Multiply

Conventional Calculation
    54
 x 84
  216
4320
4536

By simply Calculation
    54
 x 84
40/52/16
40/53/6
45/3/6

Steps involved:
We follow conventional method but we try to skip the extra work to reduce time and effort.
First we multiply the right hand side number 4 x 4 (straight line). Write down 16 as our answer
Then we multiply 5 x 4 and add it with 8 x 4 i.e. 5 x 4 + 8 x 4 (the cross). We get 52 as our answer.
Then we multiply the left hand side number 5 x 8 (straight line). Write down 40 as our answer.
Then we carry forward 1 from 16 to the left hand side as we will have only one digit. So we get 53 in the centre.
Then we carry forward 5 from 53 to the left hand side as we again will have only one digit in the centre. So we get 3 in centre and on the left hand side we get the answer 45
Our final answer is 4536

    27
 x 35
6/31/35
6/34/5
9/4/5

Steps involved:
First we multiply the right hand side number 5 x 7 (straight line). Write down 35 as our answer
Then we multiply 5 x 2 and add it with 3 x 7 i.e. 5 x 2 + 3 x 7 (the cross). We get 31 as our answer.
Then we multiply the left hand side number 2 x 3 (straight line). Write down 6 as our answer.
Then we carry forward 3 from 35 to the left hand side as we will have only one digit. So we get 34 in the centre.
Then we carry forward 3 from 34 to the left hand side as we again will have only one digit in the centre. So we get 4 in centre and on the left hand side we get the answer 9.
Our final answer is 945.

    67
 x  4

This is

    67
 x 04
0/24/28
0/26/8
2/6/8

Steps involved:
First we multiply the right hand side number 7 x 4 (straight line). Write down 28 as our answer
Then we multiply 4 x 6 and add it with 0 x 7 i.e. 5 x 2 + 0 x 7 (the cross). We get 24 as our answer.
Then we multiply the left hand side number 6 x 0 (straight line). Write down 0 as our answer.
Then we carry forward 2 from 28 to the left hand side as we will have only one digit. So we get 26 in the centre.
Then we carry forward 2 from 26 to the left hand side as we again will have only one digit in the centre. So we get 6 in centre and on the left hand side we get the answer 2.
Our final answer is 268.

Now, if we want to multiply a 3 digit number with a 3 digit number we keep in mind the following diagram.



   342
x 425
12/22/31/24/10
12/22/31/25/0
12/22/33/5/0
12/25/3/5/0
14/5/3/5/0

Steps involved:

  1. First we multiply the right hand side number 2 x 5 (straight line). Write down 10 as our answer
  2. Then we multiply 4 x 5 and add it with 2 x 2 i.e. 4 x 5 + 2 x 2 (the first cross). We get 24 as our answer.
  3. Next we multiple 3 x 5 add it to 4 x 2 and again add that to 4 x 2 i.e. 3 x 5 + 4 x 2 + 4 x 2 (the star). And we get the answer 31.
  4. Then we multiply 3 x 2 and add it with 4 x 4 i.e. 3 x 2 + 4 x 4 (the second cross). We get 22 as our answer.
  5. Then we multiply the left hand side number 3 x 4 (straight line). Write down 12 as our answer.
  6. Then we carry forward 1 from 10 to the left hand side as we will have only one digit.

-     We keep carrying on each number to the left hand side and we leave one number in each case and hence we get the number 14/5/3/5/0

  1. Our final answer is 145350.

   862
x  35

we can add a 0 to 35 and then solve as following

   862
x 035
0/24/58/36/10
0/24/58/37/0
0/24/61/7/0
0/30/1/7/0
3/0/1/7/0

Steps involved:

  1. First we multiply the right hand side number 2 x 5 (straight line). Write down 10 as our answer
  2. Then we multiply 6 x 5 and add it with 3 x 2 i.e. 6 x 5 + 3 x 2 (the first cross). We get 36 as our answer.
  3. Next we multiple 8 x 5 add it to 0 x 2 and again add that to 6 x 3 i.e. 8 x 5 + 0 x 2 + 6 x 3 (the star). And we get the answer 58.
  4. Then we multiply 3 x 8 and add it with 0 x 6 i.e. 3 x 8 + 0 x 6 (the second cross). We get 24 as our answer.
  5. Then we multiply the left hand side number 8 x 0 (straight line). Write down 0 as our answer.
  6. Then we carry forward 1 from 10 to the left hand side as we will have only one digit.

-     We keep carrying on each number to the left hand side and we leave one number in each case and hence we get the number 3/0/1/7/0

    Our final answer is 30170.

    This method should be faily simple to understand but it requires lots of practice. You have been following this method since childhood, but now you are skipping certain steps to calculate faster.

    I hope this lesson was fun and you enjoyed it as much as I enjoyed writing it down for you!

    See you tomorrow.

    Rahul Makhija

    If you have missed any of the previous days, then you can visit them now:

    Day 1
    Day 2
    Day 3
    Day 4
    Day 5



    Courses Recommended

    For students or kids: Click Here
    Getting Started Now: Click Here
    Advanced Course 1: Click Here
    Advanced Course 2: Click Here