Posted by Ann on Wednesday, January 5, 2011 at 9:44pm.
Regarding my question below, when the question talks about digits 0-7 do we include the 0. In other words, are the possible digits 0,1,2,3,4,5,6,7 or 1,2,3,4,5,6,7? Thanks again for your help.
How many odd four-digit numbers, all of the digit different can be formed from the digits 0 to 7, if there must be a 4 in the number?
- Math (Reiny) - Reiny, Wednesday, January 5, 2011 at 10:40pm
Ann, you are right,
I read the question rather superficially and did not fully register that the zero was included, and we had 8 digits instead of 7
I will also assume that a 4-digit number would not start with a 0.
so lets look at those 3 cases again.
case 1: starts with a 4 and ends with an odd, placing the odd digits in 4 ways in the 4th place.
1x6x5x4 = 120
case 1: the "4" is in the second position, but that means we cannot start with a 0
5x1x5x4 = 100 , the zero could go in the 3rd place
case 3: same as case 2 , 5x5x1x4
total = 120+100+100 = 320
This is is reference to question
- Math (Reiny) - Ann, Wednesday, January 5, 2011 at 11:03pm
Thank you so very much!!!
- Math (Reiny) - Reiny, Wednesday, January 5, 2011 at 11:07pm
You are welcome, sorry about the error.
Good for you to catch it.
Answer This Question
More Related Questions
- Math - What do the digits in the number 15 add up to? Answer 1+5=___. Using ...
- MATHS - In this addition each letter represents a digits. Different letters ...
- math - I am helping my daughter and I need help on this question in the number ...
- math - i posted this one a ways down, i apologize for double posting, but ...
- discrete math - How many strings of four decimal digits (Note there are 10 ...
- math - using digits 1-9 only once, multiply a 3 digit by a 2 digit number and ...
- FOURTH GRADE MATH - I NEED HELP WITH MULTIPLICATION!!!!!!!! MY QUESTION IS HOW ...
- math - x has 3 digits. the tens digits is half the hundreds digits. the number ...
- math (data management) - How many n-digit decimal sequences (using digits 0-9) ...
- URGENT MATHS - I got 2 questions and I've been stuck on them for days and its ...