# math

How many two digit numbers are there in base 5. I really don't understand how to figure this out. I know it's been asked already, but I still don't understand it.

1. 👍 0
2. 👎 0
3. 👁 130
1. The digits of a base 10 number goes from 0 to 9. The first digit of a two digit number (any base) cannot be zero, otherwise the number will become a 1-digit number.

So in base 10, there are 9 choices for the first digit, and 10 choices for the second, for a total of 9*10 numbers.

For a number in base 5, we have up to 5 different digits, namely 0,1,2,3,4. The digit 5, 6, ... do not exist in a number to base 5.

So the number of choices for the first digit, excluding zero, is 5-1=4. The number of choices for the second digit is 5.

So there is a total of 4*5 =20 two digit base 5 numbers, namely
10, 11, 12, 13, 14, 20, 21, 22, 23, 24, 30, 31.....34, 40, 41, 42, 43, 44.
(Remember digits 5 and above do not exist in base 5, just like we have no digit for 10 and above for base 10).

If this is still not clear, please post.

1. 👍 0
2. 👎 0
2. Mathmate-
Thank you very much, I completely understand your explanation now.

1. 👍 0
2. 👎 0

## Similar Questions

1. ### Mathematics

What is true of the number 55,555 A. Each digit has value less than the value of the digit time it's right and greater than the value of the digit itself. B. Each digit has a value 10 times the value of the digit to it's right and

2. ### balayan national highschool

The hundred thousands digits of a six-digit even number is 3 more than the thousand digit, which is twice the ones digit. Give at least four numbers that satisfy the given condition.

3. ### math

list all the 3 digit numbers that fit these clues. the hundreds digits is less than 3. the tens digit is less than 2. the ones digit is greater than 7

4. ### Math

Think of a five-digit number composed of odd numbers. The thousands digit is two less than the ten thousands digit but two more than the hundreds digit. The tens digit is two more than ones digit which is four less than the

1. ### math

i am a three digit number. my hundreds digit is three more than my ones digit.my tens digit is oneless than my hundreds digit. what numbers can i be?

2. ### Math. Explain

From the digits 1, 2, 3, and 4, how many positive integers are less than 100,000? Consider the possibilities for 5-digit, 4-digit, 3-digit, 2-digit, and 1-digit numbers and repetition of digits. 1,364 1,024 256 A telephone dial

3. ### math

how many positive 4-digit numbers are there with an even digit in the hundreds position and an odd digit in the tens position? a. 10,000 b. 5,040 c. 2,500 d. 2,250

4. ### math

the hundred thousands digit of a six-digit even numbers is 3 more than the thousand digit,which is twice the ones digit.give at least four numbers that satisfy the given condition.

1. ### GENERAL CHEMISTRY

CALCULATE THE pH AND HYDROLYSIS IN 0.10 M AlCl3 SOLUTION.Ka = 1.2 X 10-5 FOR [Al(OH2)6]+3,OFTEN ABBREVIATED Al+3.TELL WHETHER pH IS ACID OR BASE.GIVE IONIC EQUATION. Help us a little by telling us how much you know to do and

2. ### math

Name the position of the first digit of the quotient. 1. 832/4 2. 217/7 I don't understand. Someone please explain to me.

3. ### math

What is Jared's favorite six-digit number if the ten digit is his favorite digit, the sum of the hundred thousand digit and the thousand digit in his number from the largest place value to the smallest place value are consecutive

4. ### APChem

Hi I tried to understand this but I don't know why the answer is B: Which one of the following pairs cannot be mixed together to form a buffer solution: A) NaC2H3O2, HCl B)RbOH, HBr C) NH3, NH4Cl D) H3PO4, KH2PO4 E) KOH, HF The