Can someone give me a real life example of division in practice?? How does that work?
In: Mathematics
Long division works by utilising all your other arithmetic skills – multiplication, subtraction, addition, and simple division … and knowing how to apply them in solving a long division problem.
Take the example of 1/7 (one divided by seven) … you could also use 1 billion (1,000,000,000) divided by seven since we’re going to be using a lot of zeroes, and as long as we remember where we want a decimal point later it doesn’t really matter if it’s one or one billion.
First, make a list of multiples of your divisor (7) from 0*7 to 9*7 (0, 7, 14, 21, 28, 35, 42, 49, 56, & 63). This might seem simplistic, but when you have a bigger divisor it will be more useful.
Write the dividend (the number to be divided) as 1.0000000000 … or as many trailing zeroes as you like. Then select the largest number from your list of divisors that you can subtract from the dividend. … in this case it will be 0*7, because 1*7 is obviously larger than 1. Because our first subtraction was ‘0’ we place a 0 then a decimal point, as we know our answer will be less than 1
Whenever you cannot subtract a multiple of 7 you ‘borrow’ one of those zeroes, and add it to your remaining dividend … in this case that would give us ’10’ … we can now subtract 1*7 from 10, so we take that 1 and add it to the end of the ‘0.’ from before, giving 0.1
After having subtracted 1*7 from 10 we are left with a ‘3’, which we cannot wholly divide by any of our divisors, so we ‘borrow’ another ‘0’ which gives us ’30’ … and from 30 we can subtract a maximum of 4*7 (28) so we add the ‘4’ to our answer, which is now 0.14 … and we are left with ‘2’ remaining.
Again ‘borrow’ another ‘0’ so that we have ’20’, and we can subtract 2*7 from 20, meaning our answer is now 0.142 … with 6 remaining.
6 –> 60 – (8*7) –> 0.1428 & 4 remaining
4 –> 40 – (5*7) –> 0.14285 & 5 remaining
5 –> 50 – (7*7) –> 0.142857 & 1 remaining
1 –> 10 … now we’re back to our original problem, so repeating the steps above is just going to give the same answers which means our answer is going to have a repeating pattern …
0.142857142857142857…. etc.
*While not quite* ELI5 *level, this was how I learned long division when I was seven … which probably dates me somewhat :)*
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