Which of the following numbers is divisible by 8?

1. 503786

2. 505268

3. 305678

4. 703568

A number is divisible by 8 if the number formed by its last three digits is divisible by 8.

1. 503786: last three digits = 786, not divisible by 8.

2. 505268: last three digits = 268, not divisible by 8.

3. 305678: last three digits = 678, not divisible by 8.

4. 703568: last three digits = 568, and 568 ÷ 8 = 71, divisible by 8. ✓

Hence, option 4 is the correct option.