Problem number 21. In the picture, each shape stands for a different number. Which number should be written in place of the question mark? This picture shows us that the numbers at the ends of the rows and columns are the sums of the three numbers that make them up. That's what this plus sign means. So the question mark is the sum of two squares and a circle. In a problem like this, there usually is an easy way to figure out what one of the shapes stands for, and then we can go from there. In this case, we know that the same shape stands for the same number, so each of these three squares stands for the same number. And three of this number added together makes 18. What number added to itself three times is 18? It's number 6. 6 plus 6 plus 6 is 18. So the square stands for 6. We can use this information to find the value of the other shapes. 6, 6, 6, 6, and 6. Now we don't know the value of the circle, and that's the sum that we're looking for. So we need to find the value of the triangle. Here we have one triangle and two squares, but we don't know the sum, so we cannot use this row. However, in the first column, we have one square and two triangles equal to 14. We know the square stands for 6, so the two triangles will stand for 14 minus 6, or 8. If the two triangles stand for 8, then one triangle will stand for half of 8, or 4. So now we can fill this in. Now we can find the value of the circle. We have 4 plus circle plus 4 is 10. So the circle is equal to 10 minus 4 minus another 4, or 10 minus 4 is 6, and minus 4 is 2. So the circle has a value of 2. And now we know the values of all three shapes in the column of the question mark, so we just need to add them together. 6 plus 6 plus 2 is 12 plus 2, or 14. So the number that should be written in place of the question mark is 14. The answer is C.

puzzle

shapes

numbers

solution

calculation