If you look you cannot see me

by

If you look you cannot see me. If you see me you cannot see anything else. I can make anything you want happen, but later everything goes back to normal. What am I? Check the answer here.

You start with 1000 then add 40

by

You start with 1000 then add 40 add another 1000 then add 30 add another 1000 then add 20 add one more 1000 then add 10 what is your answer? Check the answer here.