1.Among all fractions $x$ that have a positive integer numerator and denominator and satisfy $$\frac{9}{11} \le x \le \frac{11}{13},$$ which fraction has the smallest denominator?
2.
What is the largest 4-digit number that is equal to the cube of the sum of its digits?
Nice answer, but how did you solve it?
I tried putting it in this form, but I don't know where to go from there.
1000a + 100b + 10c + d = (a+b+c+d)^3
=^._.^=