Qns:The difference between two numbers is 143. The sum of the two numbers is 501. Find the bigger number.
The 2 unknown numbers will be denote as A and B.
A - B = 143
Hence when -B crosses the river, it'll become +B:
A = 143 + B
When A = 143+ B,
A + B = 501
143 + B + B = 501
2B = 501 - 143
2B = 358
B = 358/2
B = 179
When B = 179,
A - B = 143
A - 179 = 143
A = 322
A = 322 and B = 179
Ans: The bigger number is 322.
Phew, I had a difficult time explaining to him why I needed to use the above method. So if anyone has a better way of explaining to the kids, do share it here, thanks!!
Use model method to explain, that would be easier I guess. Draw one big box and one small for each number.
ReplyDelete1)Subtract the difference from the sum of two numbers.
501 - 143 = 358
2)Then both the boxes will be of equal size.
3) Divide by 2 and you get the smallest number.
358/2 = 179
Smallest number is 179
4) Add the difference to the smallest number to get the biggest number.
Biggest is 179 + 143 = 322
Shade the difference part in the big box or cover it with finger so that the child can visualize.
It was not easy to explain this as well, but a little better than the traditional alzebra method.
Hope that's helpful.
Would like to hear any other methods from other parents as well.
Dear Parents,
ReplyDeleteMay I share that the children have been exposed to the use of shapes to represent certain "mystery numbers" as well? This can be found in their written paper since end last year and will be appearing this year as well. This is "algebraic" in nature. But the children understand shapes or pics better. Thus we do not introduce alphabets in class. But the concept is the same.
Thus we can do like this: (sorry not able to draw here, and I'm including the oral part as well so it may not be presented in such a nice neat way)
Circle + square = 501
Circle - square = 143
If we take the difference between the two with the greater number taking away the smaller one,
(No more circle here - one circle take away one circle) ( square - - square gives you an addition and you end up with 2 squares) ,and 501 - 143 = 358
That means, 2 squares = 358
Share equally in two parts,
One square = 179
If the square is 179, then the circle will be 501 - 179.
The circle = 322
I would encourage the children to put the numbers back into the first two maths statements formed (with the unknown shapes) to check if their answer is right, that is, whether by adding these two numbers, they will get 501, and by taking the difference, they will get 143.
Thanks for sharing the 2 different strategies!
Have a wonderful day!
Ow Yeong
Thanks for the sharing! Shall try these 2 different methods tonight to see which one Marc can relate better.
ReplyDeleteThanks for the sharing! Shall try these 2 different methods tonight to see which one Marc can relate better.
ReplyDeleteDear Parents,
ReplyDeleteA parent shared this and it worked better for her child: Am sharing this on the blog. (Have not sought permission yet to publish name so am putting the parent anonymous first. But kudos goes to this wonderful parent:-
Take away the difference between Nos. A and B
501-143 = 358
358 is the equal sum of A and B
Therefore A or B is
358/2 = 179
The bigger number is
179 + 143 = 322
This solution follows the model method as well, but I am not able to copy it here.
I will show it in class to illustrate the various methods of solution.
Thanks for being a great team!
Ow Yeong