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We divide 3 (dividend) and 4 (divisor)
We start dividing the 2 numbers...
Since 3 isnt divisible by 4 we take a decimal point and carry down a zero (0) which makes it 30.
Now we divide 4 by 30 and we get 4*7 as 28 (remaining 2)
Now one more zero (0) gets carried down and makes it 20 thus 4 divides 20 perfectly (4*5=20) 
Hence the answer 0.75