Which number must be inserted in place of the incorrect number? Show puzzle solution The number 75 must be replaced by the ...

The total value is represented by the digits in the tens and ones places of the number in column 3. This puzzle originally appeared in Spektrum der Wissenschaft and was reproduced with permission.

Only a small percentage of the population boasts an above-average IQ, so now's your opportunity to see how you measure up! ...

This is the moment a brainy three-year-old completed a slide number puzzle - in just 40 seconds. Video shows Xiao Ming skillfully maneuvering the blocks within the puzzle frame, which is also known as ...