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If x%of four-digit numbers have a repeated digit (the repeated digits do not need to be adjacent), then what is x? Express your answer as a decimal to the nearest tenth.

 Dec 12, 2019
 #1
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22.4% of four-digit numbers have a repeated digit.

 Dec 12, 2019
 #2
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a=1;b=0;c=0;d=0;p=0; cycle:if(a==b or a==c or a==d or b==c or b==d or c==d, goto loop, goto next); loop:print a*1000+b*100+c*10+d," ",;p=p+1; next:d++;if(d<10, goto cycle, 0);d=0;c++;if(c<10, goto cycle, 0);d=0;c=0;b++;if(b<10, goto cycle,0);b=0;c=0;d=0;a++;if(a<10, goto cycle,0);print"Total = ",p

 

OUTPUT =4,464 integers - have at least 2 repeated digits out of total of 9,000 integers.

So x =4,464 / 9,000 = 62 / 125 =49.6%

 Dec 12, 2019
 #3
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+1

There are  9*10*10*10 = 9000  4 digit numbers

 

There are  9*9*8*7 = 4536 that do not have repeating digits.

 

SO there are 9000-4536 = 4464 that do

 

x = 4464/9000*100 = 49.6

 Dec 12, 2019

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