
Question
Three numbers p, q and r are all prime numbers less than 50 with the property that $\displaystyle p+q=r $. How many values of r are possible?
I would think this is 0 because prime numbers have to be odd and odd + odd always equals an even number. But the answer is not 0

It's not all prime numbers odd. You forget 2 which is prime and even.
Then if p=2 and q=3 then p+q=2+3=5=r and p,q,r are all primes.
Same if p=2 and q=5 then r=7.
Check if there are any more...

wow forgot about 2...
ok
2,3
2,5
2,11
2,17
2,29
2,41
did i miss any?

OK I have another one.
When 1000^2008 is written as a numeral, the number of digits written is..
How do you go about doing this?

I don't quite understand what you want for the last one you asked $\displaystyle 1000^{2008}$
You want to know how many digits this number has?? Too many! (Rofl)

1000^1 = 1000 ( 4 digits)
1000^2 = 1,000,000 (7 digits)
1000^3 = 1,000,000,000 (10 digits)
there is pattern ^^

oo alright! so if $\displaystyle 1000^2$ has 7 digits (6 zeros) that means
$\displaystyle 2008\div2 = 1004$
$\displaystyle 1004* 6 = 6024 + 1 $ (the extra 1) is 6025!