- Monday 16 September 2019
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Mental maths is the practice of working out mathematical calculations in our mind without the need of paper, pen or calculator. It could even be thought of as manipulating numbers in the mind.
Children have the need to do mental maths every day; when thinking of how much time is left in class; or when calculating the number of points their team needs to win a game. These skills transfer into adulthood where there is an even greater need for them, such as comparing values of products or services, converting from one type of unit to another, using foreign currency, investing, building, cooking, shopping … it can be a lot!
‘What’s the point of learning this when our phones all have calculators?’
How many times have you heard this question from students? Mental maths is a very useful skill, however, students asking this question do have a point. Mobile phones and tablets have become firmly established in everyday life. They are a technology which many of us rely heavily on and with calculator apps prevalent in most, there are fewer reasons to calculate mentally.
In saying that, there is much evidence to suggest why mental maths is so important and should not be overlooked as just something that we ‘have to do’:
It strengthens the brain.
Through the practice of mental maths, students’ brains are kept sharp and their learning capabilities are boosted. While mathematical skills are supposed to be a task of the left brain, mental maths stimulates the right brain which is responsible for imagination, visualisation and creativity. Doing maths mentally requires students to think of creative solutions and visualise numbers—which involves using the right brain.
An interesting article published by The Guardian explores the significant effect mental maths has on bulking up brain muscle compared to playing a computer game. Ryuta Kawashima of Tohuku University, near Sendai in Japan, used scanners to observe children’s brains while playing computer games, as the children did a simple mental maths exercise known as Kraepelin. The idea was to show that Nintendo®-style video games were stimulating in an effort to promote their benefits to parents. But what Kawashima found was that the Nintendo® games kept busy the parts of the brain associated with vision and movement, but simple maths operations stimulated activity in both left and right hemispheres of the frontal lobe, proving that maths is one of the best ways to strengthen a brain, far more than any computer game can.
It has a positive impact on mental health.
A new study analysing the brain activity of students while doing mental maths problems found that the more a person activated a region of the brain called the dorsolateral prefrontal cortex while performing mental maths, the more likely he or she was to report being able to adapt their thoughts about emotionally-difficult situations. The study also found that greater activity in the dorsolateral prefrontal cortex was also associated with fewer depression and anxiety symptoms.
It develops observation skills.
The practice of mental maths can help to build a relationship between different things; in this case, numbers. Students become aware of how numbers interact with each other, which is an important skill required to love maths. Maths concepts are built on each other and getting a sense of numbers is important to understand complex concepts.
It increases memory.
Mental maths relies heavily on memory. So, if students need to find out 11% of 200, they will first do 10% of 200 = 20, then 1% of 200 = 2 and then add the two. So, 11% of 200 is 22. It may look challenging in the beginning but eventually they get the hang of it.
It promotes self-confidence.
If children have a better understanding of mental maths concepts, they are more likely to approach maths with a positive outlook. Regular practice of mental maths activities builds student self-confidence and esteem. It also goes without saying that they will look cool in front of their friends if they can calculate 37% of 650 without using a calculator.
Not only does the above reasoning justify your classroom mental maths programming, but the next time a student asks you this question again you will be armoured with some pretty effective and undeniable answers.
Cool mental maths tricks!
If your answer still isn’t good enough, another way to show students how effective mental maths can be is by teaching them some cool mental maths tricks like the ones below:
Multiplying by 9
Multiplying by 9 will always have a product that the digits when added together have the sum of 9.
Example:
9 x 3 = 27, 2 + 7 = 9
9 x 4 = 36, 3 + 6 = 9
9 x 45 = 405, 4 + 0 + 5 = 9
9 x 765 = 6885, 6 + 8 + 8 + 5 = 27, 2 + 7 = 9
9 x 10 231 = 92 079, 9 + 2 + 0 + 7 + 9 = 27, 2 + 7 = 9
Divisibility by 3
To see if a number is divisible by 3, add up the digits. If the sum is divisible by three, so is the number. Note: this also works for 9.
Example:
363: 3 + 6 + 3 = 12, 1 + 2 = 3
5790: 5 + 7 + 9 + 0 = 21, 2 + 1 = 3
Multiplying by 11
To multiply a 2-digit number by 11 just add the digits together and stick the answer between them.
Example:
42 x 11, 4 + 2 = 6
Now put the 6 between the 4 and 2 to get 462.
Multiplying by 5
First multiply by 10, then divide by 2.
Example:
50 x 5, 50 x 10 = 500, 500 ÷ 2 = 250
750 x 5, 750 x 10 = 7500, 7500 ÷ 2 = 3750
Pretty cool, hey?
The benefits of mental maths are numerous, with the applications of mental maths in daily life myriad. When it comes to programming mental maths lessons in the classroom, the duration of exercises does not matter so much—the frequency is what’s important, so doing them on a daily basis is essential.
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