Question

There are two similar figures below with some numbers. The left one is complete whereas one number is missing in the right one. Find a suitable number to fill in place of the question mark.

• A. 280
• B. 303
• C. 362
• D. 382

Hint:

Check if the bottom number in the complete circle equals the sum of the top, left and right numbers.

Answer 1

The Correct Option is A

An alternative way to solve this is to test each answer choice against the pattern observed in the complete circle, rather than deriving the formula first and applying it directly.

1. List the four numbers in the complete circle: top = 102, left = 09, right = 90, bottom = 201.
2. Add all four numbers: 102 + 09 + 90 + 201 = 402. This total is exactly double the bottom value, since 2 x 201 = 402. So the bottom number equals half of the total of all four numbers, which is the same as saying bottom = top + left + right.
3. Now take the incomplete circle: top = 203, left = 07, right = 70. Try each option as the bottom value and check whether top + left + right equals that option.
4. Option (2), 303: 203 + 07 + 70 = 280, which is not 303, so this option is wrong.
5. Option (3), 362: 203 + 07 + 70 = 280, which is not 362, so this option is wrong.
6. Option (4), 382: 203 + 07 + 70 = 280, which is not 382, so this option is wrong.
7. Option (1), 280: 203 + 07 + 70 = 280, which matches exactly, so this is the correct value.

The missing number is 280, confirming option (1) as the correct answer.