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 5 of 6.
Sitaram said:
7 years ago
Very easy method, Thanks @Aruna.
Kiran said:
7 years ago
How come 1400?
Chethan Prabhu said:
7 years ago
@All.
Guys don't solve this in this way. Just add the digits
Question is 1397 X 1397.
add digits
1 + 3 + 9+ 7 = 20, add again 2 + 0 = 2
So it becomes 2 X 2 = 4.
Now check options and see which sum upto 4
A) 1951609 = 1 + 9 + 5 + 1 + 6 + 0 + 9 = 31, 3 + 1 = 4. So this is the answer.
B) 1981709 = 1 + 9 + 8 + 1 + 7 + 0 + 9 = 35, 3 + 5 = 8, wrong.
C) 18362619 = 1 + 8 + 3 + 6 + 2 + 6 + 1 + 9 = 36, 3 + 6 = 9,
D) 2031719 = 2 + 0 + 3 + 1 +7 + 1 + 9 = 23, 2 + 3 = 5.
Guys don't solve this in this way. Just add the digits
Question is 1397 X 1397.
add digits
1 + 3 + 9+ 7 = 20, add again 2 + 0 = 2
So it becomes 2 X 2 = 4.
Now check options and see which sum upto 4
A) 1951609 = 1 + 9 + 5 + 1 + 6 + 0 + 9 = 31, 3 + 1 = 4. So this is the answer.
B) 1981709 = 1 + 9 + 8 + 1 + 7 + 0 + 9 = 35, 3 + 5 = 8, wrong.
C) 18362619 = 1 + 8 + 3 + 6 + 2 + 6 + 1 + 9 = 36, 3 + 6 = 9,
D) 2031719 = 2 + 0 + 3 + 1 +7 + 1 + 9 = 23, 2 + 3 = 5.
(22)
Rishi said:
6 years ago
Nice explanations. Thanks all.
(4)
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)
Deepmars said:
6 years ago
Good explanation, thanks @Pramod.
(2)
Sagar said:
6 years ago
@Aruna.
Easy, thanks for solving it.
Easy, thanks for solving it.
(2)
Pritam said:
6 years ago
Step-1: Do the sum of the digits of multiplicands then multiply both.
Step-2: If the number comes in two-digit add them.
Step-3: Add all the digits of answer untill it becomes a single digit number.
15^2 = 225
1+5 * 1+5 = 2+2+5
6 * 6 = 9
36 = 9
3+6 = 9
9 = 9
So, the answer is 225.
Step-2: If the number comes in two-digit add them.
Step-3: Add all the digits of answer untill it becomes a single digit number.
15^2 = 225
1+5 * 1+5 = 2+2+5
6 * 6 = 9
36 = 9
3+6 = 9
9 = 9
So, the answer is 225.
(11)
Nikita said:
5 years ago
How 1400 came? Please explain.
(5)
Jyotirban Pandey said:
5 years ago
How did 1400 come?
(4)
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