Q.

Estimate the difference (97-38) by rounding off each of the numbers to their nearest tens.


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a

70

b

60

c

50

d

none of these  

answer is B.

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Detailed Solution

Given the difference (97-38).
We know that if the number placed at the ones digit is less than 5, the number will become 0, and if the number is higher than or equal to 5, the number will become 10.
Thus, rounding off 97 to the nearest tens, the number placed at one's digit is equal to 7 which is greater than 5.
So, the number 97 after rounding off will be 100.
Similarly, rounding off 38 to the nearest tens, the number placed at one's digit is equal to 8 which is greater than 5.
So, the number 38 after rounding off will be 40.
Hence, our two numbers are 100 and 40, their difference will be,
100 – 40 = 60
Therefore, the correct option is 2.
 
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