math
posted by Tenecia on .
How many SevenDigit numbers less than 1,048,000 can be using the digits 0,1,4,6,7,8 and 9 ? Think: Make A List Of Possible Ways to Represent Your SevenDigit Numbers.

to have a 7digit number < 1 048 000 the first two digits have to stay.
so let's start looking at the third place
1 if we keep the 4, then the remaining digits can be
filled in 5x7x7x7 or 1715 ways
2. If we use a digit other than 4, namely a 0 or 1,
then the remaining digits can be filled in
2x7x7x7x7 or 4802 ways
for a total of 1715+4802 or 6517 ways
systematic list:
1 047 999
1 047 998
..
1 047 000
1 046 999
1 046 998
..
1 046 000