Shortcut Trick Check the sum of digits for each number. If the sum is divisible by 3, the number is divisible by 3. Option 1: 6+8+7 = 21 (Divisible by 3) Option 2: 7+1+3 = 11 (NOT divisible by 3) ∴ The correct answer is 713. Alternate Method Given: Numbers 687, 713, 927, 453. Formula Used: Divisibility rule of 3 states that a number is divisible by 3 if the sum of its digits is a multiple of 3. Calculations: ⇒ Case 1: 687 → 6 + 8 + 7 = 21. Since 21 ÷ 3 = 7, it is divisible. ⇒ Case 2: 713 → 7 + 1 + 3 = 11. Since 11 is not divisible by 3, 713 is not divisible. ⇒ Case 3: 927 → 9 + 2 + 7 = 18. Since 18 ÷ 3 = 6, it is divisible. ⇒ Case 4: 453 → 4 + 5 + 3 = 12. Since 12 ÷ 3 = 4, it is divisible. ∴ The correct answer is 713. Related Concepts: Divisibility by 9 Similar to 3, a number is divisible by 9 if the sum of its digits is divisible by 9. Divisibility by 6 A number is divisible by 6 if it is simultaneously divisible by both 2 (even number) and 3 (sum of digits rule). Prime Numbers 713 is not divisible by 3, but it is a composite number (23 × 31 = 713).