SOLUTION: Hi, i was wondering if anyone could help me. :) question- How many numbers are equal to the sum of two odd, one-digit numbers? Thank you :D

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Question 980481: Hi, i was wondering if anyone could help me. :) question- How many numbers are equal to the sum of two odd, one-digit numbers?
Thank you :D
Answer by macston(5194) About Me  (Show Source):
You can put this solution on YOUR website!
There are 5 one digit odd numbers, so
.
C=number of combinations of n things taken r at a time
n=total number of odd digits=5: r=how many to add at one time=2
C=n%21%2F%28n-r%29%21r%21
C=5%21%2F%285-2%29%212%21
C=%285%2A4%2A3%21%29%2F%283%212%21%29
C=20%2F2=10
ANSWER: There are 10 numbers that are the sum of two positive single digit odd numbers.
.
If we include negatives, there are a total of 10 odd single digit numbers:
n=10; r=2
C=10%21%2F%28%2810-2%29%21%282%21%29%29
C=%2810%2A9%2A8%21%29%2F%288%212%21%29
C=90%2F2
C=45
ANSWER 2: Including negatives, there are 45 numbers that are the sum of two single digit numbers.