+33661 There are just over 131 7's in 922 (922/7 = 131.7...), so the sum of all the multiples is given by 7*(1+2+3+...+131).
This is 7*131*132/2 = 60522
There are just over 48 19's in 922 (922/19 = 48.5...), so the sum of all these multiples is 19*(1+2+...+48)
This is 19*48*49/2 = 22344
If you meant the sum of both, then
(1) total is 60522+22344 = 82866 unless you don't want common multiples counted twice.
(2) Since there are 6 common multiples the sum of these is 7*19*(1+2+...+6) = 7*19*6*7/2 = 2793. This is counted twice, so we subtract this from 82866 to get 80073.
+33661 There are just over 131 7's in 922 (922/7 = 131.7...), so the sum of all the multiples is given by 7*(1+2+3+...+131).
This is 7*131*132/2 = 60522
There are just over 48 19's in 922 (922/19 = 48.5...), so the sum of all these multiples is 19*(1+2+...+48)
This is 19*48*49/2 = 22344
If you meant the sum of both, then
(1) total is 60522+22344 = 82866 unless you don't want common multiples counted twice.
(2) Since there are 6 common multiples the sum of these is 7*19*(1+2+...+6) = 7*19*6*7/2 = 2793. This is counted twice, so we subtract this from 82866 to get 80073.
