Wednesday

August 27, 2014

August 27, 2014

Posted by **nancy** on Sunday, September 16, 2012 at 12:59pm.

2-how many three digit numbers are not even and do not divide by 5 ?

- math -
**David Q/R**, Sunday, September 16, 2012 at 1:39pmThere are 900 three-digit numbers in total (100 to 999 inclusive), and every odd-numbered one is even, i.e. 1st = 100, 3rd = 102, 5th = 104, 7th = 106 etc. There are as many odds and evens in 900 consecutive integers, so exactly half of them are even, i.e. 900/2 = 450.

For part 2, consider just the first 10 integers, i.e. 100 to 109. Of these, 101, 103, 105, 107 and 109 are not even, and of these, only the third one is divisible by 5. So 4 out of the first 10 satisfy the stated conditions for inclusion. Now consider the next 10, i.e. 110 to 119. For any N, if N is odd then (N+10) is also odd, and if N does not divide by 5 then (N+10) does not divide by 5. So exactly the same logic applies to these next ten as to the previous 10. Ditto the next 10, ditto the next 10 after that, etc etc. So the total number between 100 and 999 should be 4 x 900 / 10 = 360.

**Related Questions**

math30 - The number of three digit or four digit even numbers that can be formed...

math - given the digits 0,1,2,3,4,5,6, and 7 find the number of possibilities in...

math - sophia is making raffle tickets for the schools give away drawing.she ...

math - i am a three digit number. my hundreds digit is three more than my ones ...

math - my thousand digit is half my ones digit.my houndreds digit is odd and ...

math - I am a 2-digit number with a 1-digit decimal. I am bigger than 54 but ...

Math - Tami wrote the even numbers between 325 and 337. The sum of the hundreds...

math - Tami wrote the even numbers between 325 and 337.the sum of the hundreds ...

math - The number uses every number 0-9 the numbers are used only once the ...

math - how many 7 digit telephone numbers can be made if every other digit is ...