# different number of ways

• Jul 20th 2008, 06:48 PM
AbigailVD
different number of ways
In how many ways can 12 be written as sum of two or more positive whole numbers? (changing the order of addition does not count as a different way.)

(A) 12
(B) 13
(C) 14
(D) 15
(E) 16

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How many different postive numbers are equal to the product two odd one-digit numbers?

(A) 25
(B) 15
(C) 14
(D) 13
(E) 11

• Jul 21st 2008, 02:00 PM
masters
Quote:

Originally Posted by AbigailVD
In how many ways can 12 be written as sum of two or more positive whole numbers? (changing the order of addition does not count as a different way.)

(A) 12
(B) 13
(C) 14
(D) 15
(E) 16

Must be another restriction missing....like you can't repeat digits in your sum. In other words, 2+2+8 would not be allowed since there are two 2s.

1+11
2+10
3+9
4+8
5+7

1+2+9
1+3+8
1+4+7
1+5+6
2+3+7
2+4+6
3+4+5

1+2+3+6
1+2+4+5

I get 14. No special algorithm, though. Just eyeballed it. Could've missed some, too
• Jul 21st 2008, 02:09 PM
masters
Quote:

Originally Posted by AbigailVD

How many different postive numbers are equal to the product two odd one-digit numbers?

(A) 25
(B) 15
(C) 14
(D) 13
(E) 11

Don't know if I fully understand what you're asking, but I'll take a stab at it.

1 x 1
1 x 3
1 x 5
1 x 7
1 x 9

3 x 3
3 x 5
3 x 7
3 x 9

5 x 5
5 x 7
5 x 9

7 x 7
7 x 9

9 x 9

That makes 15.