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MY SON IS IN SINGAPORE 4A. WE SWITCHED HIM TO SINGAPORE IN 3B (I'M THINKING WE MISSED SOMETHING BECAUSE THIS BOOK DOESN'T TEACH HOW TO DO THIS PROBLEM AT ALL).
IT'S IN THE TEXTBOOK PRACTICE 2B

THE DIFFERENCE BETWEEN TWO NUMBERS IS 2184. IF THE BIGGER NUMBER IS 3 TIMES THE SMALLER NUMBER, FIND THE SUM OF THE TWO NUMBERS.

THE ANSWER BOOK SAYS THE ANSWER IS 4368. I HAVE NO IDEA HOW TO GET TO THIS ANSWER AND EXPLAIN IT TO HIM. PLEASE HELP!

This is solved using the bar diagrams that Singapore uses. I think they are really pretty ingenious, but it can take a while to wrap your head around those bars. In this problem when you draw it out, you can see that the big number is 3 times the small number and the total is actually 4 times the small number and the difference is 2 times the small number. Once you see that you can get to the answer several ways by finding how much the small number is and then multiplying by 4 or just seeing that the difference is actually 2 times the small number so the total is 2 times the difference. Hopefully that isn't too confusing. Since a picture is worth a thousand words, check out this old post that has a picture showing the bar diagrams: viewtopic.php?f=6&t=9119&hilit=+singapore HTH!

THANK YOU, THANK YOU, THANK YOU!!! WE'VE ONLY HAD A COUPLE OF THESE BAR MODELS (WHICH ARE REALLY GREAT) SO FAR. I KNEW I SHOULD BE ABLE TO SHOW HIM WITH A BAR MODEL, BUT I JUST COULDN'T FIGURE OUT HOW. FEELING REALLY BLESSED TO BE A PART OF THIS MESSAGE BOARD