Consider the following triangular arrangement of numbers.
1
2 3
4 5 6
7 8 9 10
11 12 13 14 15
• • • • • •
The middle number of the 51st row is?
-- James.
Consider the following triangular arrangement of numbers.
1
2 3
4 5 6
7 8 9 10
11 12 13 14 15
• • • • • •
The middle number of the 51st row is?
-- James.
It is obvious that line 'n' ends with the number n*(n+1)/2.
( line 2 ends with 2*3/2=3
line 3 ends with 3*4/2=6 and
line 4 ends with 4*5/2=10)
Therefore line 50 will end with the number 50*51/2 =1,275
middle number in the 51st row is the 26th number in the row.
Hence Middle number in the 51st row is 1,275 +26 = 1,301.
-- James.
the middle no of 51 st row is 197
Re: find out the number.
is it 1300
i think it is 1301!
James ravid please verify this!
bye
:)
NEVER SAY DIE.
Yeah i too think the answer is 1301...
Thanks
Manoj
and I confirm it wud b 1301
Please check this
James had already given answer.Re: find out the number. -- Answer
It is obvious that line 'n' ends with the number n*(n+1)/2.
( line 2 ends with 2*3/2=3
line 3 ends with 3*4/2=6 and
line 4 ends with 4*5/2=10)
Therefore line 50 will end with the number 50*51/2 =1,275
middle number in the 51st row is the 26th number in the row.
Hence Middle number in the 51st row is 1,275 +26 = 1,301.
-- James.
(Second post in the thread)
Cheers!
Kalayama
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