Speed Maths Session 2B

Dear Friends,


THE SPEED MATHEMATICS METHOD


I am now going to show you the speed mathematics way of working with two digit near to 100 number multiplication in this session


The problem now looks like this:


98


x 96


We now look at each number and ask, how many more do we need to make 100?


We start with the 98. If we have 98, how many more do we need to make 100?


The answer is 2. 98 plus 2 equals 100. We write 2 next to the 98. Our equation now looks like this:


98 - 02


x 96






We now go to 96. How many more to make 100? The answer is 4.


We write 4 next to the 96.


This is how the problem looks now:


98 - 02


x 96 - 04






We now take away, or subtract, crossways or diagonally. We either


subtract 2 from 96 or 4 from 98. It doesn’t matter which way we subtract—


the answer will be the same, so choose the calculation that looks


easier. Two from 96 is 94, or 4 from 98 is 94. Either way the answer is 94.


You only take away one time.


since it is 100 base we multiply 94 with 100 so its 9400


Write 9400 below answer line.


98 - 02


x 96 - 04


-----------


94










For the last part of the answer, you “times,” or multiply, the numbers


next to actual multiplication number. What is 2 times 4? Two times 4 means two fours added


together. Two fours are 8. since the compliment as two digit add zero in front of 8 as 08. Write the 08 as the last part of the answer.


The answer is 9408.


98 - 02


x 96 - 04


------------ -


9408










Any clarification kindly revert back to me.






Practice: Try this out (Don't skip this since higher level need this practice)






a) 96 × 96 = e) 98 × 94 =
b) 97 × 95 = f) 97 × 94 =
c) 95 × 95 = g) 98 × 92 =
d) 98 × 95 = h) 97 × 93 =






More fun to follow.


Note: We can instead of asking how many more to make it 100, you can use the formula we learned in 2A. eg. 98 complement no. is "all by 9 and last by 10" the answer is 9-9 = 0 , 10-8 = 2, so the complement no. is 02 and for 96, 9-9 = 0 , 10-6 = 4 and 04 is the complement no.


Thanks,


-Ramesh


9886556628