Aptitude - Numbers - Discussion
Discussion Forum : Numbers - General Questions (Q.No. 5)
5.
1397 x 1397 = ?
Answer: Option
Explanation:
| 1397 x 1397 | = (1397)2 |
| = (1400 - 3)2 | |
| = (1400)2 + (3)2 - (2 x 1400 x 3) | |
| = 1960000 + 9 - 8400 | |
| = 1960009 - 8400 | |
| = 1951609. |
Discussion:
55 comments Page 4 of 6.
Rohit said:
8 years ago
Just multiply.
1397
1397
After multiplying for the second time just add and see the last 3digits are coming to 609 then its easy to ascertain or you can take the nearest whole number, whichever seems easy for you.
1397
1397
After multiplying for the second time just add and see the last 3digits are coming to 609 then its easy to ascertain or you can take the nearest whole number, whichever seems easy for you.
Isha said:
8 years ago
1+3+9+7=20 =>2+0=2.
1+3+9+7=20 =>2+0=2.
2+2=4.
a) 1+9+5+1+6+0+9=31 =>3+1=4 (4 equal to 4) so it is answer.
b)1+9+8+1+7+0+9=35 =>3+5=8 (8 not equal to 4) wrong.
1+3+9+7=20 =>2+0=2.
2+2=4.
a) 1+9+5+1+6+0+9=31 =>3+1=4 (4 equal to 4) so it is answer.
b)1+9+8+1+7+0+9=35 =>3+5=8 (8 not equal to 4) wrong.
Sowmi said:
8 years ago
Nice explanation @Rahul Jadhav.
Ajith said:
8 years ago
@Isha.
Whether it is applicable to all type of problems like this?
Whether it is applicable to all type of problems like this?
Shweta said:
7 years ago
Nice explanations thank you all.
Rohini said:
7 years ago
Thank you all for explaining the solution.
Aruna said:
7 years ago
1397*1397=?
1+3+9+7=20=2+0=2.
1+3+9+7=20=2+0=2.
2*2=4.
Option
A, 1951609 because
1+9+5+1+6+0+9=31=3+1=4 so it is the answer.
1+3+9+7=20=2+0=2.
1+3+9+7=20=2+0=2.
2*2=4.
Option
A, 1951609 because
1+9+5+1+6+0+9=31=3+1=4 so it is the answer.
(5)
Venkat Reddy Mula said:
7 years ago
@Aruna.
Your method is perfect, Thanks.
Your method is perfect, Thanks.
Atif said:
7 years ago
1397 * 1397 = 1951609.
(1)
AKSHAY said:
7 years ago
The multiplication of sum of digits = the some of digits of the answer.
example = 24*6 = 144 =1+4+4 = 9.
now 2+4 *6 = 36= 3+6=9.
So if the answer is given we can use this method.
Now, back to question.
1397*1397
1+3+9+7 * 1+3+9+7,
=2 * 2 = 4.
And, in option, 1951609 = 1+9+5+1+6+0+9 = 4.
example = 24*6 = 144 =1+4+4 = 9.
now 2+4 *6 = 36= 3+6=9.
So if the answer is given we can use this method.
Now, back to question.
1397*1397
1+3+9+7 * 1+3+9+7,
=2 * 2 = 4.
And, in option, 1951609 = 1+9+5+1+6+0+9 = 4.
(1)
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