Respuesta :

there are 3 different numbers
slot method

how many 3 digit numbers?
321
312
123
132
213
231
 

6 numbes

how many 2 digit numbers?
12
21
13
31
23
32

6 numbers

how many 1 digit numbers
1
2
3

3 of them

6+6+3=15


15 different number, yah you ar right