Mike D. answered • 08/01/22
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Well the first digit has to be 0,1,2,3,4,5,6
If it is 6, there is one possibility 6 7 8 9
If it is 5, then we can choose the other three from (6,7,8,9) so 4 C 3 = 4 ways, then we just put them in increasing order
If it is 4, then we choose the other three from (5,6,7,8,9) so 5 C 3 = 10 ways
if it is 3, then 6 C 3
2, then 7 C 3
1 then 8 C 3
0 then 9 C 3
So 9C3 + 8C3 + 7C3 + 6C3 + 5C3 + 4C3 + 3C3
Peter R.
08/01/22
Mike D.
It's unclear. If a 4 digit number is interpreted as a number consisting of four digits, as 0 is a digit there is no reason to exclude 0 as a first digit (unless the questions states specifically the first digit is non-zero), colloquially a four digit number should have a non-zero first digit but mathematically there is no reason here why the first digit cant be 008/01/22
Mike D.
The fact Brainly says something doesn't mean it is correct, there are many mathematically incorrect statements on websites08/01/22
Mike D.
They are not checked for rigor.08/01/22
David W.
If the first digit is '0', is it a 4-digit number?08/01/22