Question

[Dương Nguyễn]

Each of the integers 226 and 318 have digits whose product is 24. How many three-digit positive integers have digits whose product is 24?

Answer 1

[Trần Thu Hà]

The factors of 24 are: 1, 2, 3, 4, 6, 8, 12, 24

We know that we can't have a two digit factor in one of our three digit numbers(it can't fill in one digit), so we are left with:

1,2,3,4,6,8

Now, we can just bash out unique cases:

138

146

226

234

138 = 3! = 6 ways

146 = 3! = 6 ways

226 = 3!/2! = 3 ways

234 = 3! = 6 ways

add all these up, and we get:

6+6+3+6 = 21 

Answer 2

[Dương Nguyễn]

tv đc ko banj