Estimate the factors 2,047 x 508 and solve

The multiplication property of zero states that the product of any number and 0 is 0. what must be true about either a or b to make ab=0

Someone this asap for a group of students attends a basketball game. * the group buys x hot dogs at the concession stand for $2 each. * the group buys y drinks at the concession stand for $3 each. the group buys 29 items at the concession stand for a total of $70. how many hot dogs did the group buy?

How do i simply this expression (quadratic formula basis) on a ti-84 or normal calculator?