A short math puzzle shared by Ukrainian news agency UNIAN challenges solvers to complete five plus five using a hidden arithmetic rule.
The brain teaser presents a series of four mathematical equations displayed on a digital graphic. The first three lines show three plus three equal to nine written as zero nine, six plus six equal to 18, and nine plus nine equal to 27. Solvers are asked to determine what number should replace the question mark in the final row of five plus five.
Standard addition does not apply to the problem. Under normal arithmetic rules, three plus three equals six rather than nine. The puzzle requires solvers to identify a single underlying pattern that consistently explains every line shown on the image rather than stopping at the first obvious calculation.
Solution for the math riddle
To find the correct answer, solvers are advised to examine the relationship between the left and right sides of each equation. Instead of using complex formulas, comparing the numbers in each row reveals a simple arithmetic operation that applies equally across all examples.
The solution requires multiplying the first number in each equation by three. In the first line, three multiplied by three equals nine, which appears on the graphic formatted as zero nine. In the second line, six multiplied by three yields 18, and in the third line, nine multiplied by three gives 27. Following this same rule for the final row, five multiplied by three equals 15, making 15 the correct answer.
Background on digital logic puzzles
Logic puzzles and mathematical riddles are widely popular on digital media platforms and news sites. These brain teasers test cognitive flexibility by replacing standard mathematical symbols with alternative logical rules. News organizations often publish such visual puzzles to engage readers with quick mental exercises that encourage analytical thinking. Ukrainian Independent Information Agency, known as UNIAN, is a major news agency based in Kyiv that produces broad news coverage alongside lifestyle features and interactive content.
Related feature stories
UNIAN regularly publishes interactive brain teasers and lifestyle tests. The agency previously released a psychological personality test designed to reveal an individual's deep personal fears. Recent feature reporting from the outlet has also covered why parents preserve childhood drawings for decades, how Greek retirees enjoy longer pensions than most Europeans, and how a miner accidentally discovered the largest gold nugget ever found in Alaska.
