Friday, January 16, 2009

Multiplication of 2 numbers that are near to 100 or 1000

This tip is suitable for multiplying two numbers that are near to 100. For example, 103 x 104 and 97 x 98.

Example 1:

To calculate 103 x 104:

  1. Add the the ones from the multiplicand to the multiplier.
    103 + 4 = 107.

  2. Multiply the ones from the multiplier with the ones from the multiplicand.
    3 x 4 = 12.

  3. Concatenate the results from step 1 and 2. Therefore, 103 x 104 = 10712.


Example 2:


To calculate 1005 x 1002:

  1. Add the the ones from the multiplicand to the multiplier.
    1005 + 2 = 1007.

  2. Multiply the ones from the multiplier with the ones from the multiplicand. Prepend a zero to the result.
    5 x 1 = 010.

  3. Concatenate the results from step 1 and 2. Therefore, 1005 x 1002 = 1007010.


Example 3:


To calculate 97 x 98:

  1. Subtract from 10, the ones from multiplicand.
    10 - 8 = 2.

  2. Subtract from multiplier, the result from step 1.
    97 - 2 = 95.

  3. Subtract from 10, the ones from multiplier.
    10 - 7 = 3.

  4. Multiply the result from step 3 with the result from 1. Prepend a zero.
    2 x 3 = 06.

  5. Concatenate the results from step 2 and step 4. Therefore, 97 x 98 = 9506.


Example 4:


To calculate 993 x 995:

  1. Subtract from 10, the ones from multiplicand.
    10 - 5 = 5.

  2. Subtract from multiplier, the result from step 1.
    993 - 5 = 988.

  3. Subtract from 10, the ones from multiplier.
    10 - 3 = 7.

  4. Multiply the result from step 3 with the result from 1. If you get a one digit number, prepend two zeroes, otherwise prepend just one zero.
    5 x 7 = 035.

  5. Concatenate the results from step 2 and step 4. Therefore, 993 x 995 = 988035.


Exercise:


If domain name is cost $9.90 each, what is the cost if you want to buy 92 domain?

5 comments :

  1. Great technique! Very useful today where most of the prices around end with 9-something(eg 9.99, 9.97).

    <abbr>KHs last blog post..Words from The Old Man</abbr>

    ReplyDelete
  2. perghhhhhhhhhhh neh betul2 minimalist neh.
    hehe i like !

    ReplyDelete
  3. A Vedic matrix 0...9 is given below!

    ..0.....1.....2.....3.....4.....5.....6.....7.....8.....9
    ----- ----- ----- ----- ----- ----- ----- ----- ----- -----
    0
    ----- ----- ----- ----- ----- ----- ----- ----- ----- -----
    1
    ----- ----- ----- ----- ----- ----- ----- ----- ----- -----
    2
    ----- ----- ----- ----- ----- ----- ----- ----- ----- -----
    3
    ----- ----- ----- ----- ----- ----- ----- ----- ----- -----
    4
    ----- ----- ----- ----- ----- ----- ----- ----- ----- -----
    5
    ----- ----- ----- ----- ----- ----- ----- ----- ----- -----
    6
    ----- ----- ----- ----- ----- ----- ----- ----- ----- -----
    7
    ----- ----- ----- ----- ----- ----- ----- ----- ----- -----
    8
    ----- ----- ----- ----- ----- ----- ----- ----- ----- -----
    9...........................................97

    97 is '3 less than' a 100. It means (+97-3) position
    89 is '11 less tham' a 100. It means(+89-11) position'

    See that 97-11= 86 and 89-3= 86
    Merge (-3)*(-11)= 33 to right of 86 as 8633.
    97*89= 8633

    ReplyDelete
  4. .0….1….2….3….4….5….6….7….8….9
    —– —– —– —– —– —– —– —– —– —–
    0
    —– —– —– —– —– —– —– —– —– —–
    1
    —– —– —– —– —– —– —– —– —– —–
    2
    —– —– —– —– —– —– —– —– —– —–
    3
    —– —– —– —– —– —– —– —– —– —–
    4
    —– —– —– —– —– —– —– —– —– —–
    5
    —– —– —– —– —– —– —– —– —– —–
    6
    —– —– —– —– —– —– —– —– —– —–
    7
    —– —– —– —– —– —– —– —– —– —–
    8
    —– —– —– —– —– —– —– 97 —– —–
    9

    97 is a position that has 97 ones before it.
    So (+97-3)is written!
    89 is (+89-11)!
    Basics shall be correct!

    ReplyDelete