Aptitude - Numbers - Discussion
Discussion Forum : Numbers - General Questions (Q.No. 134)
134.
287 x 287 + 269 x 269 - 2 x 287 x 269 = ?
Answer: Option
Explanation:
| Given Exp. | = a2 + b2 - 2ab, where a = 287 and b = 269 |
| = (a - b)2 = (287 - 269)2 | |
| = (182) | |
| = 324 |
Discussion:
5 comments Page 1 of 1.
Ranjan kumar ojha said:
4 years ago
Thanks for explaining the answer @Chethan.
(1)
Pavan said:
4 years ago
@Kuldeep.
It's (287-269) = 18.
It's (287-269) = 18.
Kuldeep said:
5 years ago
How become 18^2? Please explain.
Chethan Prabhu K said:
7 years ago
By Digit Sum method:
287 * 287 + 269 * 269 - 2 * 287 * 269.
Step 1 : Cancel all 9's and all combinations of 9.
It becomes
8 * 8 + 8 * 8 - 2 * 8 * 8 (287= 7+2 = 9, So cancel it)(269 = cancel 9, 2+6 =8)
64 + 64 - 2 * 64.
1 + 1 - 2 * 1(1 = 6+4 = 10 = 1 +0 = 1)
=> 0.
Check options = 324 = 3+2+4 = 9, 9 means 0 remember. So that's the answer.
287 * 287 + 269 * 269 - 2 * 287 * 269.
Step 1 : Cancel all 9's and all combinations of 9.
It becomes
8 * 8 + 8 * 8 - 2 * 8 * 8 (287= 7+2 = 9, So cancel it)(269 = cancel 9, 2+6 =8)
64 + 64 - 2 * 64.
1 + 1 - 2 * 1(1 = 6+4 = 10 = 1 +0 = 1)
=> 0.
Check options = 324 = 3+2+4 = 9, 9 means 0 remember. So that's the answer.
Esai arasi said:
9 years ago
Explain me in digit sum method.
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