Great Tips for Faster Mental Multiplication

In your bank coaching centre you may have been told multiple times that appearing for the IBPS PO or SBI exam is not just about maximum accuracy but also effective time management. Especially when you are solving the tougher quantitative questions, it is easy to get overwhelmed and nervous. 

By learning these quick mental math tips in multiplication, you will be able gain some confidence in your paper solving technique while also saving significant time. 

• Multiplying by the Powers of 5 

When you need to multiply one number, by another that happens to be a power of 5, for instance, 36 X 5, remember that 5 = 10/2. You will find that finding the answer of 36 X 10 and then dividing it by 2 is a lot easier than multiplying 36 by 5. 

What if the question is more complex than that and you need to multiple 36 by a larger number such as 25? Here you need to recognize that 25 = 100/4 to simplify the calculation process. The rule of thumb is to remember that powers of 5 are always some multiple of 10 divided by an integer. This way you will be able to quickly find answers to complex multiplications where one of the numbers is a power of 5. 

• Squaring Numbers that End in 5 

While squaring a two-digit number that ends in 5 remember that the last two digits of the answer will always be 25. The digits before that can be attained by multiplying the first digit of the number by that number that is one greater. For instance, the square of 45 will end with a 25 and the digits before that will be 4X5 = 20. This means that the square of 45 = 2025. 

• Multiplying Lots of 9s 

If you are expected to multiply any number of 9, 99, 999 or any other number that is one less than the power of 10 here is what you can do - if the problem is 44X9, you can also represent it as 44 X (10-1). 

44 X (10-1) = 44 X 10 – 44 X 1 = 440 = 44 = 396. 

If the question involved more complex multiplication such as 44 X 99, you can convert this problem into 44 X (100-1) and solve it the very same way. This means that in problems such as these, you simply need to multiple the number by the next higher power of 10 and subtract the original number. 

You will be taught a host of other tips and tricks in your SBI coaching such as multiplying by the powers of 2, doubling and halving to multiple faster, etc. Each one of these tricks can be mastered with practice, allowing you to save significant time when solving the math section in your bank exam. The more practice you do the easier it will be for you to use them in your exam.