Question

Shari wrote the numbers from 1 to 16 on a card.

Next, she crossed out all the numbers which are factors of 80.
Then, she crossed out all the numbers which are multiples of 3.
How many numbers were not crossed out?​

Answer 1

factors of 80: 1,2,4,5,8,10,16,20,40,80
so we cross out 1,2,4,5,8,10,16
the first 5 multiples of 3 are: 3,6,9,12,15
so we cross out those number and then we are left with 7, 11, 13 and 14
the answer is: 4 numbers were not crossed out