Question
how many 7 digit numbers can less than 1,048,000 can be made using digits 0,1,4,6,7,8 and 9?
Answers
MathMate
Start from left to right:
We have no choice with the first three digits, they must be 104 or else the final number will be greater than 1048000.
The fourth digit can only be a number less than 8, namely 6 and 7 from what's left.
The remaining three digits can form 6 numbers each, namely
abc
acb
bac
bca
cab
cba
So if you had kept count until now, you would have the answer.
We have no choice with the first three digits, they must be 104 or else the final number will be greater than 1048000.
The fourth digit can only be a number less than 8, namely 6 and 7 from what's left.
The remaining three digits can form 6 numbers each, namely
abc
acb
bac
bca
cab
cba
So if you had kept count until now, you would have the answer.