Answer:
We assume the three toppings must be different.
Explanation:
Cheese :
3
choices
Toppings :
8
choices for the first,
7
for the second and
6
for the third, a total of
8
×
7
×
6
=
336
, IF the order of toppings were important -- which it isn't. This number is called the number of permutations .
Three things can be ordered in 6 ways (try this), so in the 336 permutations, there are groups of 6 that amount to the same combination :
123=132=213=231=312=321, etc.
So we have to divide the number of permutations by the number of orders to reach the number of combinations:
There are thus 336 : 6 = 56 possibilities for the toppings.
Since we need cheese AND toppings we multiply:
Number of different pizzas: 3 x 56 = 168.
Calculator : if you have the nCr function the answer would be:
3 x 8 nCr 3 = 168
Explanation: