Math tricks and mental math shortcuts are used to perform speedy calculations. Many of us know at least a trick or two because they are easy to remember and handy to use. But why or how do these tricks work?
This is the first of a series of posts that will discuss math tricks and mental math shortcuts. Aside from the algorithm that will be taught in this series that will benefit everyone, we will also investigate why they work.
The Trick: Squaring Numbers Ending in 5
Squaring numbers ending in 5 is probably the most popular among the math tricks and mental shortcuts. Below is the algorithm of the trick.
- Take 25 as the last two digits of the product of the factors.
- Add 1 to the tens digit of one of the factors.
- Take away 5 from both the factors, and multiply the remaining numbers.
- Append the product in the third step to the left of the result in the first step. » Read more
Sanjay Guilati (author) has been teaching computer and mathematics in Bhilai , state Chattisgarh in India for 15 years. Currently he is a teacher in a senior secondary school and he is also involved in teacher training. His online work can be found in Mathematics Academy.
Students often fear multiplication of numbers, which involve lot of 9’s in them. However the truth is exactly the opposite. The higher the number of 9’s in the question, the easier it is to calculate the correct answer.
There can be three cases with multiplication with series of 9’s
- Multiplying a number with an equal number of 9’s
- Multiplying a number with more number of 9’s
- Multiplying a number with less number of 9’s
Here we are discussing Case 1 only and leaving the rest two cases for the readers to explore. » Read more
Sanjay Guilati (author) has been teaching computer and mathematics in Bhilai , state Chhattisgarh in India for 15 years. Currently he is a teacher in a seniorsecondary school and he is also involved in teacher training. Sanjay is the writer of the new blog titled Mathematics Academy.
Vedic Mathematics 2 – Squaring Numbers Ending in 5
by Sanjay Gulati
In Vedic Mathematics, there are two types of techniques: specific techniques and general techniques. The specific techniques are fast and effective but can only be applied to a particular combination of numbers. On the other hand, Vertically and Crosswise method is one of the general techniques in Vedic Mathematics , as it can be used to multiply numbers of any possible combination of digits. Thus general techniques have a much wider scope of application than specific techniques because they deal with a wider range of numbers. Here first we will discuss some of the specific techniques.
» Read more