Posted by greeny on Friday, August 17, 2012 at 10:40pm.
how many different positive fourdigit integers can be formed if the first digit must be 2, the last digit cannot be zero, and digits may be repeated?
I know the answer is 900 but I'm not sure how I would get the answer? thanks!

math  David Q/R, Saturday, August 18, 2012 at 4:35am
If the first digit must be 2, and digits can be repeated, you can forget about the leading digit and just look for every THREEdigit integer (INCLUDING leading zeros) whose last digit isn't zero. That's every integer between 000 and 999 (of which there are 1000), excluding the 10% of them that end in zero (of which there are 100)  which makes 900 in total.

math  Reiny, Saturday, August 18, 2012 at 7:31am
Only 1 choice for the 1st spot, 10 choices for the 2nd, 10 choices for the 3rd and 9 choices for the 4th
1x10x10x9 = 900
Answer This Question
Related Questions
 math  How many different positive fourdigit integers can be formed if the ...
 college math  How many different fourdigit numbers can be formed from the ...
 mathpermutuation  a four digit serial number needs to be created using digits ...
 MATH ( PROBABILITY)  Security codes in Fiji are made up of 4 digits. How many ...
 Math  How many odd fourdigit numbers, all of the digit different can be formed...
 Math  i am a four digit number. all of my digits are different. my first digit ...
 math  There are 900 threedigit integers. The number of threedigit integers ...
 Math  It's a riddle question. All six digits in the number even remember that ...
 Math  It's a riddle question. All six digits in the number even remember that ...
 Math. Explain  From the digits 1, 2, 3, and 4, how many positive integers are ...
More Related Questions