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
To run the these figures to 3 decimal places
you need to count from the digit after the decimal point until you reach the 3rd number which is 2
so now the answer is 2470.283
This is because the decimal point lies between 2 and 7 and since 7 is great than 5 we add 1 to the 2 making it 3