How can you EASILY explain how to calculate ((640 x 15) / 480)) or ((640 / 480) x 15))

How can you EASILY explain how to calculate ((640 x 15) / 480)) or ((640 / 480) x 15)) ?

OK.
640/480 is the same as 64/48
64 is divisible by 8 = 8
48 is divisible by 8 = 6
15 is divisible by 3 = 5
6 is divisible by 3 = 2

so you have (8/2)*5 = 20

You can explain this through Order of operations , BEDMAS ( Brackets, Exponents, Division, Multiplication, Addition, Subtraction). BEDMAS is the order you use to solve a question. Since brackets come first, solve the numbers inside the bracket. In this case, (640 x 15)= 9600 or (640/ 480)= 1.33333. Since there are no exponents in this question, you go onto to division. So, 9600/ 480 = 20 , or 1.3333 x 15= 19.9995 (if you round it up , it is 20)
You can read more about it at http://math.about.com/od/glossaryofterms…

ok
so


write it out


640 x 15

480

assuming you dont have a calculator, you can either do the caluclation by hand which is not very hard

or you can simplify it


480 can be seperated to 32 x 15, you can do this stepwise, I simply did it quickly


so you have 640 x 15 / 32 x 15, the 15 cancels out, leaving 640 / 32 simplify further you get 320 / 16 or 160 / 8 or 80 / 4 or 40 / 2 or 20


try the next one

You can make the calculation easier by reducing the numbers involved by cancelling factors top and bottom

First divide top and bottom by 10
gives
64*15/48

now divide top and bottom by 8

gives

8*15/6

now divide top and bottom by 3

gives

8*5/2

2 goes into 8 four times

we are left with
4*5 = 20

All the numbers end in '5' or '0' hence they will divide by '5'

640 x15/480 = 128 x 3 / 96

Since '3' and '96' are factors of '3' they will cancel down

128 x 1 / 32

Since 128 and 32 have '4' as a factor they will cancel down

32 x 1/8
and '8' will cancell down '32'
Hence
4 x 1/1 = '4' THE ANSWER!!!!