Maths Tricks

The rule which you need to follow while subtracting a large number from 1,000 is: Subtract every number except the last from 9 and subtract the final number from 10.

For example:

1,000 – 656

Step 1: Subtract 6 from 9 = 3

Step 2: Subtract 5 from 9 = 4

Step 3: Subtract 6 from 10 = 4

The answer is 344.

When we need to multiply the number 5 by an even number, use this maths shortcut to find the answer.

For example, 5 x 6 =

• Step 1: Cut the number being multiplied by five in to half. This makes the number 6 to be number 3.
• Step 2: Add a zero to the number and you have your answer. In this case, the answer will be 30.

5 x 6 = 30

When we need to multiply an odd number with 5, the formula is a bit different.

Let us consider 5 x 7.

• Step 1: Subtract one from the number that we need to multiply by 5, in this instance the number 7 becomes the number 6.
• Step 2: Now cut the number 6 into its half, which makes it the number 3. Make 5 the last digit. The number produced is 35, which is the answer.

5 x 3 = 15

The same can be applied to bigger odd and prime numbers.

The quick Maths trick to know when a number can be evenly divided by these certain numbers:

• 10 if the number ends in 0
• 9 when the digits are added together and the total is evenly divisible by 9
• 6 if the number is even and when you add the digits, the answer is evenly divisible by 3
• 8 if the last three digits are evenly divisible by 8 or are 000
• 5 if it ends in a 0 or 5
• 4 if the number ends with 00 or a two digit number that is evenly divisible by 4
• 3 when the digits are added together and the result is evenly divisible by the number 3
• 2 if it ends in 0, 2, 4, 6, or 8

This is an easy method that is helpful for multiplying any number by 9. Here is how it works:

Let’s use the example of 9 x 3.

Step 1: Subtract 1 from the number that is being multiplied by 9.

3 – 1 = 2

The number 2 is the first number in the answer to the equation.

Step 2: Subtract that number from the number 9.

9 – 2 = 7

The number 7 is the second number in the answer to the equation.

So, 9 x 3 = 27

Finding a percentage of a number is always a tricky process, but if you’ll think about it in the right terms, you’ll find that there’s a fast percentage finding trick which can save your time. For instance, to find out what 5% of 235 is, follow this method:

• Step 1: Move the decimal point over by one place, 235 becomes 23.5.
• Step 2: Divide 23.5 by the number 2, the answer is 11.75. That is also the answer to the original equation.

Let’s use the number 35 as an example.

• Step 1: Multiply the first digit by itself plus 1.
• Step 2: Put a 25 at the end.

35 squared = [3 x (3 + 1)] & 25

[3 x (3 + 1)] = 12

12 & 25 = 1225

35 squared = 1225

When multiplying large numbers, if one of the numbers is even, divide the first number in half, and then double the second number. This method will solve the problem quickly. For instance, consider

20 x 120

Step 1: Divide the 20 by 2, which equals 10. Double 120, which equals 240.

Then multiply your two answers together.

10 x 240 = 2400

The answer to 20 x 120 is 2,400.

Multiplying numbers that end in zero is actually quite simple. It involves multiplying the other numbers together and then adding the zeros at the end. For instance, consider:

200 x 400

Step 1: Multiply the 2 times the 4

2 x 4 = 8

Step 2: Put all four of the zeros after the 8

80,000

200 x 400= 80,000

Practicing these fast math tricks can help both students and teachers improve their math skills and become secure in their knowledge of mathematics—and unafraid to work with numbers in the future.

There are many more Maths Tricks which you should know. The tricks are: