all integers from 102 thru 1000
divide bi 9 & add the leftovers
yu hav 899 numbers
thats 99.9 sets av 9 numbers
eech set av 10 numbers hav leftover=0, 1, 2, 3, 4, 5, 6, 7, 8
1 set sum=36
100 sets=3600
then chek a fyu numbes at both ends
102/9=11 with leftover=3
1000/9=111 with leftover=1
lak leftover=2, su anser=3600-2=3598