Math and Arithmetic

# How many two digit numbers that have digits that add up to twelve?

###### Wiki User

###### December 16, 2009 4:10AM

39

48

57

66

75

84

93

I see ** 7**. I think that's all of them.

## Related Questions

###### Asked in Math and Arithmetic

### How many 4 digit numbers have 6 as their second digit?

There are 9 digits that can be the first digit (1-9);
for each of these there is 1 digit that can be the second digit
(6);
for each of these there are 10 digits that can be the third
digit (0-9);
for each of these there are 10 digits that can be the fourth
digit (0-9).
→ number of numbers is 9 × 1 × 10 × 10 = 900 such numbers.

###### Asked in Math and Arithmetic

### How many numbers can you make from 650271 without repeating a digit?

1,956 different numbers can be made from 6 digits. You can
calculate this by using the permutation function in a summation
function, like this:
Σ6k=1 6Pk = 6P1+6P2+...+6P5+6P6
What this does is calculate how many 1 digit numbers you can
make from 6 digits, then how many 2 digit numbers can be made from
6 digits and adds the amounts together, then calculates how many 3
digit numbers can be made and adds that on as well etc.