Simple Math Tricks for Civil Service Exam

The most difficult scope of the Civil Service Examination is the Mathematical or the Problem Solving part. Knowing some tricks to compute faster will definitely help a lot.

Although these tips are intended for kids, I'm sure it will still help or at least refresh your knowledge.

Here are some tricks to help you on your way.

-    Multiplying by 10, 100, or any number that starts with a 1 and is followed by zeros is really easy. Just add the number of zeros to the number you are multiplying by. So, 6 x 1,000,000 = 6,000,000.

-    Multiplying by5 can be easy. To multiply 5 by 6, count by fives six times until you get to 30. All multiplication is really a series of additions: 3 x 5 is the same as 5 + 5 + 5 = 15.

-    To multiply any single digit by 9, it is easiest to use your hands. Spread all then fingers in front of you. For 9 x 3, put down your third finger from the left, your left middle finger. Then, count how many fingers are to the left of that finger (2) and how many fingers are to the right (7).
So, 9 x 3 = 27. Try this trick with other factors.

-    Multiplying by 4 is a little harder. But think about this and it will make it easy. To multiply something by 4, just double the number twice. So, instead of thinking about 8 x 4, think of the operation as 8 + 8 = 16; 16+16 = 32. So, 8 x 4 = 32.

-    To multiply any two-digit number by 11 is a little harder but there is a trick.

• For this example we will use 36.
• Separate the two digits(3__6). (Notice the space between them.)
• Add the 3 and the 6 together (3 + 6 = 9).
• Put the resulting 9 in the hole 396. That’s it! 11 x 36 = 396

The only thing tricky to remember is that if the result of the addition is greater than 9, you only put the “ones” digit in the hole and carry the “tens” digit from the addition.
For example 11 x 57 --> 5__7 --> 5 + 7 = 12 put the 2 in the hole and add the 1 from the 12 to the 5 in to get 6 for a result of 627. 11 x 57 = 627.

source: www.worldalmanacforkids.com