784^(1/2)

Question

\sqrt{784} =

A. 28
B. 32
C. 38
D. 56
E. 112

sashiim20 · Accepted Answer

30^2 = 900

Hence answer must be lower than  30 .

All other options are higher than  30  except A.

Hence  Answer A .

PKN · Answer

Unit digit in 784 is 4. Hence, the possible square root number must possess an unit digit of 2. Discard B,C, and D options.

Square of a 3 digit number always yield a number with greater than or equal to 5 nos of digits. Discard option E.

Ans. (A)

ArjunJag1328 · Answer

Unit digit is 4. Hence we can boil it down to A & C

Try squaring both options.

28^2 = 784
38^2 = 1444

Answer is A

philipssonicare · Answer

The units digit is the result of the units digits of its multiples. So, in this equation, the square root must have a units digit that multiplied by itself will equal 4.
0^2=0
1^2=1
2^2=4
3^2=9
4^2=6
5^2=5
6^2=6
7^2=9
8^2=4
9^2=1

This leaves numbers ending in 2 and 8. Options ABCE.

Simplify
100^2=10,000, so can't be E
40^2=1600, so likely not C
30^2=900, so can't be B or C

A

bebs · Answer

$\sqrt{784} $ = $\sqrt{4 × 196} $ = $\sqrt{4} $ × $\sqrt{196} $ = 2 × 14 = 28 ==> Answer is   A

Kinshook · Answer

\sqrt{784} =

784 < 900
 \sqrt{784} < \sqrt{900} = 30

IMO A

Bunuel  Is this not self-made question? 
Is this question suitable for GMAT?

Bunuel · Answer

It's tagged as GMAT paper test. Not sure though.

The question itself is good for practice.

ragav182 · Answer

pair the number from right to left first. Look at the unit digit of the number under the square root.

Here it is 4. hence, Square root of the number will either have 2 or 8 in the unit's place. 
next would be taking 7(7 don't have the pair here). We should think which square of a number is less than 7. We have 4 (square of 2) is less than 7. Hence, tens place will have 2,

we have two answers, 22 or 28. Now, we need to decide which would be the correct answer choice for the question.
we have a square of 25 is 625. 784 is greater than 625, So 28 would be the right answer choice. 
A is the answer.

You can try other numbers like 1024, 1369.

thyagi · Answer

784 = 2^4*7^2
sqrt 784 = sqrt(2^4*7^2) = 2^2*7 = 4*7 = 28.. (A)

Abhishek009 · Answer

Units digit must be 2 (as the square of the same will have a units digit as 4) - Reject (D) & (E)

30^2 = 900 ,  Thus, correct answer must be less than 30 , hence reject (B) & (C), thus, correct answer must be (A)

sunshineeee · Answer

I calculate 25^2 = 625 (every square of digit end with 5 -> (x)*(x+1) - first digit + 25)
so
25^2 = (2*3)+25 => 625

and square root of 784 must be around 28.

aakash233 · Answer

Testing Backwards ( A concept from Manhattan Prep)
Since the answers are in an increasing order. start from B and if B doesnt match try D.
When we start with B we find out the square of B is 1024 so the answer must be less than 32 and the only possible answer is A)24

784^(1/2)

Prep Toolkit

Top 5 GMAT Debrief Videos

615 to 715 in 15 Days (Ria's Strategies)

More than Quant/Verbal Abilities: Speed vs. Accuracy

745 with Only Self-Prep and GMAT Club

From 555 to 765: 210-point Improvement

Perfect 805 Score Debrief by Julia

My Rewards

GMAT Problem Solving (PS) Questions

784^(1/2)

Prep Toolkit

615 to 715 in 15 Days (Ria's Strategies)

More than Quant/Verbal Abilities: Speed vs. Accuracy

745 with Only Self-Prep and GMAT Club

From 555 to 765: 210-point Improvement

Perfect 805 Score Debrief by Julia

My Rewards