Wednesday

October 22, 2014

October 22, 2014

Posted by **carlton** on Tuesday, April 3, 2012 at 9:06pm.

(a) have exactly three digits which are 9s?

- discrete math -
**MathMate**, Tuesday, April 3, 2012 at 9:17pmThink of 3 9's to which we have to insert a fourth digit x(which is not a nine).

This can be in the four following ways.

X999 or 9X99 or 99X9 or 999X

In each case X can represent 9 possible digits including 0 but excluding 9.

So the number of strings is 4*9=36.

**Answer this Question**

**Related Questions**

MATH - Need Answer to the Following Please: Using the 9 digits, 1, 2, 3, 4, 5, ...

Math - Using the 9 digits, 1, 2, 3, 4, 5, 6,7, 8 and 9 you can arrange four ...

Math Help Please - Can you Please explain the answer that I received of 2469? It...

Math - Received answer to the following question from Jishka. (2469) Would you ...

Physics - Talking about significant figures, my Physics textbook lists 5 rules ...

Math - Need Answer to the Following Please: Using the 9 digits, 1, 2, 3, 4, 5, ...

math-probability - A state lottery has a daily drawing to form a four-digit ...

Discrete Math - What is the probability that a fair coin lands Heads 4 times out...

math - the binary system is used for computer programming. a binary number ...

Math Help Please - Would you please explain the steps you used to get the answer...