Help! I think it’s d but I don’t know

Look at this pattern ; 1,4,9, number 10000 belongs in this pattern . what’s the place of this number?

Neal buys a board game. he pays for the board game and pays $1.54 in sales tax. the sales tax rate is 5.5%. what is the original price of the board game, before tax

Afitness center has 2 membership plans one has a low dollar sign up fee of 15 dollars and costs 38 dollars per month to join. a second plan has a higher sign up fee of 78 dollars but a lower monthly fee of 31 dollars for what number of days of the month is the coat the same