Math Is Fun Forum

ian noble

Guest

division problem

hi ppl,

i'm in the process of rivising maths for entry into college. I know how to do division the spacesaver way, (which I find easiest). But that way of dividing I am unable to work out 18/45. Whats the easiest way to work out this amount?

many thanks
ian.

luca-deltodesco

Member

Registered: 2006-05-05

Posts: 1,470

Re: division problem

for more complicated divisions, use Long Division:

for something like this, you can take a big shortcut and save space by using intuition.
In this case, note: that if you take 18 and make it 180, you get 180/45 = 4. and then divide by 10 to get the answer 0.4

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ian noble

Guest

Re: division problem

ah right i see thanks

but what if the sum was

16/25

sorry to be a pain hehe 

John E. Franklin

Member

Registered: 2005-08-29

Posts: 3,588

Re: division problem

.
     __0_________
25 |1 6. 0 0 0 0
      - 0
      ______
       1 6 0

Now 25 adds up to 150 if 6 times of 25's.

     __0.6_______
25 |1 6. 0 0 0 0
      - 0
      ______
       1 6 0
     - 1 5 0
    ________
          1 0 and bring down another 0.

Now 25 can add up to 100 if 4   25's are used...

     __0.6_4_____
25 |1 6. 0 0 0 0
      - 0
      ______
       1 6 0
     - 1 5 0
    ________
          1 0 0
        - 1 0 0
      ________

              0  Yeah!! Zero remainder, so decimal is complete.  Answer is 0.64

Last edited by John E. Franklin (2007-07-19 06:55:55)

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mathsyperson

Moderator

Registered: 2005-06-22

Posts: 4,900

Re: division problem

That one's quite nice because multiplying by 4 gives you a denominator of 100.
16/25 = 64/100 = 0.64.

For the first one, I would have simplified the fraction to 2/5 before converting it into decimal.

There's not really a single easy method that works all the time, the best thing is to look at the question and decide what strategy to use.

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Maths&Me

Member

Registered: 2007-07-24

Posts: 3

Re: division problem

Yep, Mathsyperson was right. There is each diff. method for each problem. So juz try to think and practise more so that you can solve any problz fast and easy.
Okie, but for me, a calculator will do great!