One day, Lee decides to write down the numbers 1.....999

Lee chooses one of the digits written down at random. What is the probability that Lee chooses a 7?

i think this means it's asking for the number of 7 digits from 1....999

Guest Jan 29, 2020

#3**+2 **

Not sure about that answer

I count up in my head 300 7's

out of 2889 digits (see previous answer)

300/2889 =100/963

ElectricPavlov Jan 29, 2020

#4**+1 **

One day, Lee decides to write down the numbers 1.....999

How many times does 7 appear.

Lets see.

Units

Each decade 7 apears once. 100 decades so that is 100 times

Place value 10

Each century seven appears 10 times, 10 centuries so that is 100 sevens

Place value 100

Each millenium seven appears 100 times

So I get 300 times. You got 297. Who is wrong?

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If 7 appears 300 times it stands to reason that so do 1,2,3,4,5,6,8, and 9 do too.

How about 0

units first decade not at all so that is 99 times

tens first century not at all so that is 90 times

hundreds first milenium not at all so that is 0 times

So zero appears 189 times I think

300*9+189=2889 digits altogether.

**so I get 300/2889 Same as EP.**

I could easily have miscounted.

Melody Jan 29, 2020