Aptitude - Numbers - Discussion
Discussion Forum : Numbers - General Questions (Q.No. 71)
71.
397 x 397 + 104 x 104 + 2 x 397 x 104 = ?
Answer: Option
Explanation:
| Given Exp. | = (397)2 + (104)2 + 2 x 397 x 104 |
| = (397 + 104)2 | |
| = (501)2 = (500 + 1)2 | |
| = (5002) + (1)2 + (2 x 500 x 1) | |
| = 250000 + 1 + 1000 | |
| = 251001 |
Discussion:
4 comments Page 1 of 1.
Anonymous said:
7 years ago
397*397 + 104*104 + 2*397*104.
1*1 + 5*5 + 2*1*5,
1+7+1,
9.
251001 = 9.
Apply Sum of a digit of multiplication = sum of digit of product.
1*1 + 5*5 + 2*1*5,
1+7+1,
9.
251001 = 9.
Apply Sum of a digit of multiplication = sum of digit of product.
Vennela said:
8 years ago
We can do this through the digital sum verification instead of calculating (501)^2.
501=5+0+1 = 6 &6^2=36.
Now 3 + 6 = 9
Hence digital sum is 9.
By optional verification option with digital sum.
9is the answer.
In the options 251001=2+5+1+0+0+1 = 9.
Hence that's the answer.
501=5+0+1 = 6 &6^2=36.
Now 3 + 6 = 9
Hence digital sum is 9.
By optional verification option with digital sum.
9is the answer.
In the options 251001=2+5+1+0+0+1 = 9.
Hence that's the answer.
(1)
Tanweer said:
1 decade ago
It can also done through (a+b)^2 formula?
Narasingarao said:
1 decade ago
When 2x500 = 1000, then 2x1 must also be considered.
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