How many different numbers can you make out of 1,2,3 and they can't have two of the same numbers in 1 problem (can't be decimals) I think it 15?

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