Calculating long multiplication problems requires you to learn about the multiplication tricks which would help you in solving your problems. You would find it easier to multiply the 1-digit, 2-digit, and even 3-digit numbers. But for the larger numbers, it would take you quite some time to solve. For making your multiplication easier, here are a few easy multiplication tricks for fast multiplication that would help you in the preparation for the competitive exams.
But, before you move forward with the maths multiplication tricks, let’s recap on the definitions of the numbers that are used in the multiplication methods.
Multiplicand refers to the number multiplied.
Multiplier refers to the number that multiplies the first number.
Have a look at this example:
While multiplying 23 x 11, the number 23 is called the multiplicand and the number 11 is called the multiplier.
You must know that every multiplication operation consists of 2 numbers which are like twins. This would make it easier for you to remember. This is one of the fast multiplication tricks that would help you.
Say for example you forgot what 7 x 2 is. But you might remember that 2 x 7 = 14. In this manner, you only have to remember half of the multiplication table.
There are many maths tricks for fast multiplication that would help you in solving your math problems faster. Let’s take a look at each one by one.
1. Multiplying by 2
If you have to multiply a number by 2, you can add the number by itself. In simpler words, double the number.
For example, 6 x 2 = 6 + 6 = 12
2. Multiplying by 4
Multiplying a number by 4 is easy. All you need to do is double the number and then double it again.
Consider 8 x 4. The double of 8 is 16 and the double of 16 is 32.
3. Multiplying by 5
If you have to multiply a number by 5, you can do it very easily. Reduce the number to its half and then multiply it with 10.
For example, consider 8 x 5. Reduce the number 8 to half, which is 4, and then multiply it by 10. This would give you 40.
Alternatively, you can first multiply the number by 10 and then reduce it to its half.
Consider 9 x 5. 9 multiplied by 10 gives you 90 and then reducing to its half gives you 45.
Keep in mind that when you multiply a number by 5, the pattern of the last digit of the result is alternate between 5 and 0. It goes like 5, 0, 5, 0, 5, and so on. Its like 5, 10, 15, 20, 25, etc.
4. Multiplying by 6
When you multiply an even number by 6, both the numbers would end in the same last digit.
For example, consider:
2 x 6 = 12
4 x 6 = 24
6 x 6 = 36
5. Multiplying 7 and 8
When you have to multiply 7 and 8 together, remember the numbers 5, 6, 7, and 8.
56 = 7 x 8
6. Multiplying by 8
Multiplying a number by 8 requires you to double the number, then double the resulted number, and again double the resulted number.
Consider 6 x 8. The double of 6 is 12, the double of 12 is 34, and the double of 24 is 48.
7. Multiplying by 9
Multiplying a number by 9 is a result of multiplying it by 10 and then subtracting the number itself from the result.
Consider 6 x 9. Multiply the number 6 by 10 and it results in 60. Subtracting the number 6 from the result 60 and it gives you 54.
Also, when you multiply a number by 9, there is a pattern that follows in the ones and tens digit places.
The ones digit follows 9, 8, 7, 6, 5, and so on – 09, 18, 27, 36, 45, 54, etc.
The tens digit follows 0, 1, 2, 3, 4, and so on – 09, 18, 27, 36, 45, 54, etc.
You can also take some help from your hands! For example, if you want to multiply 9 x 8, take your 8th finger down and then start to count 7 and 2. You would get 72. This is an easy way to learn multiplication.
8. Multiplying by 10
To multiply a number by 10, just put a zero after it.
For example, 2 x 10 = 20.
9. Multiply by 11
This method works for multiplying numbers up to 9 by 11. Simply repeat the number itself for the result.
Consider 5 x 11 = 55.
10. Multiply by 12
To multiply a number by 12, simply multiply it by 10 first and then add the number to the double of it.
For example, consider 4 x 12. Multiply the number 4 by 10 which gives 40. And then add 40 to the double of this number which is 4 x 2 = 8. So, 40 + 8 = 48.
11. Multiply by 15
To multiply a number by 15, first, multiply it with 10 and then add the half of it to the result you get for getting the final answer.
Consider 4 x 15. Multiplying 4 by 10 you get 40 and adding the half 20 to it gets you 60.
4 x 15 = 40 (4 x 10) + 20 (40/2)
12. Multiplying by 20
Multiplying a number by 20 is very easy. Just multiply the number by 10 and then double it.
Consider 20 x 7. Multiplying 7 by 10 gives you 70 and then doubling it gives you 140.
1. How to multiply 2-digit numbers by 11?
Multiplying a 2-digit number by 11 is quite simple. Write the digits apart and add them both. The result of the addition goes as the middle digit of the answer.
Consider the following example:
2. How to multiply numbers that are close to the power of 10?
Multiplying 2 numbers that are close to the power of 10 utilises a base method where the powers of 10 like tens, hundreds, etc. are used. It includes cross subtraction and multiplication of the sums.
Take a look at this example which uses a base of hundreds for multiplication of two 2-digit numbers.
Consider the multiplication of 99 and 97.
Take the difference between both these numbers from the number 100 and place them on the right side of the column.
The result would be 99 – 100 = -1 and 97 – 100 = -3.
The next step is to cross add either of the set of numbers so that you get the first part of your answer. You can either take 99 + (-3) or 97 + (-1) = 96.
Both would give you the same result and this is your first half of the answer.
The next step is to multiply the smaller numbers which are -3 and -1. Multiplying them would give you 03 which is your second half of the answer.
Hence, your answer is 9603.