6. Given $a=\frac{11 \times 66+12 \times 67+13 \times 68+14 \times 69+15 \times 70}{11 \times 65+12 \times 66+13 \times 67+14 \times 68+15 \times 69} \times 100$, find: the integer part of $a$ is

what?