1/(1997×1998)+1/(1998×1999)+1/(1999×2000)+.1/(2005×2006)+1/(2006×2007)+1/2007

1/(1997×1998)+1/(1998×1999)+1/(1999×2000)+.1/(2005×2006)+1/(2006×2007)+1/2007

1/(1997×1998)+1/(1998×1999)+1/(1999×2000)+.1/(2005×2006)+1/(2006×2007)+1/2007
=1/1997-1/1998+1/1998-1/1999+...+1/2006-1/2007+1/2007
=1/1997

99 there are 49 even numbers out of which 48 numbers are taken. If the average number is 49 and 5 / 12, what is the number not taken

2+4+6+-----+98=2450
The number not taken is 2450 - (49 and 5 / 12) * 48 = 78

-What is the sum of the first 99 consecutive integers in the series of degrees 49, - 48, - 47..., 2004

-49 to - 1 has 49 numbers
There are 49 numbers from 1 to 49
One of them is 0
49 + 49 + 1 = 99 numbers
The sum is 0