Solution: (a)
\(\displaystyle ?\approx 11because11\times 11\times 11=1331\)
and \(\displaystyle 10\times 10\times 10=1000\)
Without pen and paper,
Out the options 1000 is 10 multiplied three times. So, our answer should be some near to this number so, by approximation we can easily say that the answer is 11. And also we can see that if we multiply 30 two times it is already 900, so cannot have a number that is 30 or more than it. Hence (a) is the answer
Solution: (d)
\(\displaystyle ?=\sqrt{{9355}}\approx 95\)
Without pen and paper,
9355 is in between 8100 and 10000, whose square roots are 91 and 100. SO, out the options 95 is the only number which can satisfy the conditions. So, when you come across the mcq on approximation like these. Try to analyse and answer the questions, especially when the options have large differences. If the options are very close to each other, then go with other methods.
