find out the number.

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 = [B]1,301[/B].

-- James.

the middle no of 51 st row is 197

is it 1300

i think it is 1301!
James ravid please verify this!

bye

Yeah i too think the answer is 1301...

Thanks
Manoj:)

and I confirm it wud b 1301

Please check this
[QUOTE] 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.[/QUOTE]

James had already given answer.
(Second post in the thread)

Cheers!
Kalayama