Q2 of 67 Page 101

Find the cube root of the following by looking at the last digit and using estimation.

91125

Let n3 = 91125


Here, the unit’s place digit is 5;


∴ The units digit of n must be 5.


Let us split the number 91125 as 91 and 125


Now, 43 < 91 < 53 = 125


∴ 403 = 64000 < 91000 < 503 = 125000


Since, the unit’s place digit of n is 5, the only possible number is 45.


Also, 453 = 91125


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