Question

how many 4-digit numbers contain no 8's or 9's ?

Answer 1

can't wait to see this
i have no idea

Answer 2

The first digit cannot be a 0, 8 or 9: 7 possibilities
The second, third and fourth digits cannot be 8 or 9 and so: 8 possibilities each

7 * 8 * 8 * 8 I think.

Answer 3

i think it might be harder than that

Answer 4

if it really means "or" then the first digit could be an 8 or a 9

Answer 5

we make a slot for each digit...