How many positive integers are there that (in base ten) have four digits and only use the digits 0,1,4 and 9 (such as 4199)?
2007-11-12 07:01:01 · 4 answers · asked by ra_liv93 1 in Science & Mathematics ➔ Mathematics
with repetition
4^4 - 4^3=192
4^4=number of ways of arranging digits
4^3 = number of ways that 0 come at the end
if there is no repetition
so it is 4! -3! =24 -6 = 18
2007-11-12 07:12:44 · answer #1 · answered by mbdwy 5 · 2⤊ 0⤋
192
There are 4 slots, 3 numbers available in the first one since you can't start with 0, 4 in each of the others. So that 3x4x4x4 which is 192.
2007-11-12 07:05:25 · answer #2 · answered by Marley K 7 · 0⤊ 0⤋
The 1st digit can be 9,4, or 1
the 2nd digit can be 9,4,1,or 0
Same for 3rd and 4th digit
Total = 3*4^3 = 192
2007-11-12 07:07:45 · answer #3 · answered by ironduke8159 7 · 0⤊ 0⤋
you are the motive force of a school bus. the 1st end you %. up 6 teenagers, the 2nd end, you drop off 2 and %. up 7, the third end you %. up 10 teenagers and drop off 3. Then the fourth and 5th end you drop off 4 at each and every end and %. up 7 on the 5th end. Now tell me, who's the bus motive force? the respond: You
2016-10-16 06:40:58 · answer #4 · answered by ? 3 · 0⤊ 0⤋