Math Trick 3: The Answer is Always 1089

This is the third part of the Math and Multimedia Math Trick Series.  The first two tricks are multiplying by 11 and squaring numbers ending in 5.

As I have promised, I will teach you more math tricks that will impress your friends. The most exciting part, however, is not actually the trick but why the trick works. In this post, we are going to learn math trick which we will call magic 1089, a trick I learned at BasicMathematics.com.

The 1089 Math Trick

Step 1: Think of a 3-digit number where its digits are decreasing.

Step 2: Reverse the order of the digits.

Step 3: Subtract the number in step 2 from the number in step 1.

Step 4: Reverse the order of the difference in step 3.

Step 5: Add the numbers in step 3 and step 4.

The result is 1089.  » Read more

Math Puzzle: Where is The Missing Square?

If you have already found answer to the missing area puzzle, you might want to try the mysterious missing square below. The largest triangle in the first figure is made up of two smaller triangles and two L-shaped polygons.

The largest triangle below (well, technically it’s not really a triangle) is also made up of the same polygons mentioned above. » Read more

Math Puzzle: Where is the Missing Area?

The square below is made up of two triangles and two trapezoids. The dimensions of the square is $13$ by $13$, which means that the area is $169$ square units.

The same polygons above are used to create the rectangle below. The dimensions of the rectangle is $8$ by $21$, which means that the area is $168$. » Read more

1 3 4 5 6 7 9