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 2 of 6.
G.Sravani said:
1 decade ago
1397*1397 = 7*7=49
7*9=63
7*3 = 21
.......779
9*7 =63
9*9 = 81
3*7 = 21
.....779
.... 73
.....1
== 609
In option A contain last three digits as 609.
So Answer is " A "
7*9=63
7*3 = 21
.......779
9*7 =63
9*9 = 81
3*7 = 21
.....779
.... 73
.....1
== 609
In option A contain last three digits as 609.
So Answer is " A "
ABD said:
4 months ago
1397 = 1 + 3 + 9 + 7 = 20.
1397 = 1 + 3 + 9 + 7 = 20.
20 * 20 = 400 = 4 + 0 + 0 = 4.
From options
A) 1951609 = 1 + 9 + 5 + 1 + 6 + 0 + 9 = 31,
3 + 1 = 4.
4 = 4. Hence ANSWER.
1397 = 1 + 3 + 9 + 7 = 20.
20 * 20 = 400 = 4 + 0 + 0 = 4.
From options
A) 1951609 = 1 + 9 + 5 + 1 + 6 + 0 + 9 = 31,
3 + 1 = 4.
4 = 4. Hence ANSWER.
(34)
Surya said:
9 years ago
Hello, @Thukki.
Thank you for sharing about Digital Sum method. What if the option has another number which also have 4 as Digital Sum. Will this work foe all the problems?
Thank you for sharing about Digital Sum method. What if the option has another number which also have 4 as Digital Sum. Will this work foe all the problems?
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.
Rahul jadhav said:
1 decade ago
If you want to multiply this type of big no follow the step:
1397 * 1397 = ?
1397*1400 = 1955800.
and (1397+3 = 1400) So 1397*3 = 4191.
1955800-4191 = 1951609.
1397 * 1397 = ?
1397*1400 = 1955800.
and (1397+3 = 1400) So 1397*3 = 4191.
1955800-4191 = 1951609.
Thukki said:
9 years ago
In shortcut method:
Digital sum (D. S) method i.e 4.
D.S of 1397 is 2, so 1397*1397 is 2*2 = 4.
Now out of all the options, the D.S of option a is 4.
Digital sum (D. S) method i.e 4.
D.S of 1397 is 2, so 1397*1397 is 2*2 = 4.
Now out of all the options, the D.S of option a is 4.
Prashant said:
1 decade ago
Shortcut: Digital sum (D. S) method i.e 4.
D.S of 1397 is 2, so 1397*1397 is 2*2 = 4.
Now out of all the options the D.S of option a is 4.
D.S of 1397 is 2, so 1397*1397 is 2*2 = 4.
Now out of all the options the D.S of option a is 4.
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)
Shivam said:
4 years ago
1397 * 1000 = 1397000,
1397 * 300 = 419100,
1397 * 90 = 125730,
1397 * 7 = 9779.
1397000 + 419100 + 125730 + 9779 = 1951609.
1397 * 300 = 419100,
1397 * 90 = 125730,
1397 * 7 = 9779.
1397000 + 419100 + 125730 + 9779 = 1951609.
(101)
Pramod said:
6 years ago
1397=1+3+9+7=20.
1397=1+3+9+7=20.
20*20=400=4+0+0=4.
From options
A) 1951609=1+9+5+1+6+0+9=31,
3+1=4.
4 = 4. Hence ANSWER.
1397=1+3+9+7=20.
20*20=400=4+0+0=4.
From options
A) 1951609=1+9+5+1+6+0+9=31,
3+1=4.
4 = 4. Hence ANSWER.
(127)
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