Tuesday, September 20, 2011

Really ... How this works?

Fast trick for mental Mathematics.
Click here to watch how it works.
Can you explain how this works?

4 comments:

  1. 98*97= 100*97 - 2*97
    = 9700-194

    ReplyDelete
  2. Shawn Liew Hong Wei9/21/2011 01:05:00 PM

    Round off 98 as it is nearer to 100.

    Now the statement is 100 * 97 which is 9700.

    Then we need to minus of 2 * 97.

    To do that, I would -

    2 * 100 = 200.

    Then the number is now 9500.

    100 - 97 = 3.

    2 * 3 = 6.

    9500 + 6 = 9506.

    98 * 97 is equal to 9506

    ReplyDelete
  3. Round off the larger number to 100 to make the calculations simpler and we would have 100*97 (98*97). After we round off the larger number, we would have 2*97 as the 2 comes from 100 - 98 (The larger number).
    Hence, the equation would be:
    100*97 - 2*97 (The minus comes from the fact that 2 comes from 100-98) = 9506

    ReplyDelete