Browse · harp Print → smc counting and probability senior Problem How many pairs (m,n) of integers satisfy the equation m+n=mn? (A) 1 (B) 2 (C) 3 (D) 4 Solution — click to reveal If m+n=mn, mn−m−n=(m−1)(n−1)−1=0. Then (m−1)(n−1)=1, and (m,n)=(2,2)or(0,0). The answer is 2. Final answer B ← Previous problem Next problem →