GATE 2017 EE (EE2) – Question 8

General Aptitude · Quantitative Aptitude: Data Interpretation, Arithmetic and Number Computation · 2 marks · Multiple choice

X is a 30-digit number beginning with digits 47. How many digits does $X^3$ have?

90 digits
91 digits
92 digits
93 digits

Practise this question in The GATE Grind →

Show answer and explanation

Correct answer: (A) 90 digits

Explanation

The leading digits imply $4.7\times10^{29}\le X<4.8\times10^{29}$. Cubing gives a lower bound $103.823\times10^{87}$ and upper bound $110.592\times10^{87}$.

Both lie between $10^{89}$ and $10^{90}$. Every integer in that interval has 90 digits. Therefore **X³ has 90 digits, A**.

More Quantitative Aptitude: Data Interpretation, Arithmetic and Number Computation questions

GATE 2017 EE (EE2) Q9 – The number of roots of ex+0.5x2-2=0 in [−5,5] is
GATE 2016 EE (EE2) Q3 – Pick the odd one out from 13,23,33,43,53.
GATE 2016 EE (EE2) Q5 – If 9y-6 =3, then y2-4y/3 is
GATE 2016 EE (EE2) Q6 – The graph gives installed capacity and actual cement production, in tonnes, for nine…
GATE 2016 EE (EE2) Q9 – Shaquille O’Neal succeeds at 60% of free throws. Assuming independent attempts with this…
GATE 2016 EE (EE2) Q10 – The units digit of 211870+1461273424 is .

All Quantitative Aptitude: Data Interpretation, Arithmetic and Number Computation questions →