If p, q and r are prime numbers such that pq + r = 73, what is the least possible value of p + q + r?
because p,q,r is a prime number,pq+r=73 , ''the odd number'' multiply ''the odd number'' equal ''the odd number'' and ''the odd number'' plus ''the even number'' equal ''the odd number''. number.
We have 2 case:
case 1:r is even. so r = 2
case 2:p or q is even
example:p is even.so p=2
q isn't the prime number(eliminate)