Find the no. of strictly increasing sequences of positive integers begin with 1 and end with 1000 ?

Dear Sanchit Gupta

between 1 and 1000 we have 998 positive intiger

first term of series is 1

last term of series is 1000

in between these two term 998 term can be added

and each 998 positive intiger can occur in 2 ways either it will appear or not

so number of posible sequence is   1* 2*2*2*2.........998 times *1

                                              =2⁹⁹⁸