Mental math, or ‘math in your head’ as some people like to call it, is somewhat of a dying art due to the fact that, as a society, we have become over-reliant somewhat on technology to take care of everything for us. But the ability to do mental math cannot be overstated: not only is it incredibly practical for completing little daily tasks, but it actually relates to something called number sense, which is really important for young learners. Number sense can be defined as the way in which numbers can be manipulated mentally in order to complete various calculations. And it is proven that number sense directly corresponds with a learner’s ability to perform algebraic equations at a later stage, because they act upon the same principle. Number sense is a skill that pays off down the line, and what in essence you are doing is learning to use numbers more flexibly: something that is vital if success in algebra is to be achieved, for example, but is also a great ‘life’ skill. Those who possess number sense employ a flexible approach which sees them deconstruct numbers in order to add them together in various ways which make more sense. It is akin to a linguist’s ability to play with words in order to make an interesting sentence, or the way a musician manipulates notes in order to create different songs. Someone with number sense doesn’t follow a rigid structure. And here’s the thing: number sense is something that anyone can develop. There is this pervasive feeling that you are either a numbers person, or you are not, and while this may be true for someone who is an absolute math genius, everybody can learn number sense. After all, learning number sense is a lot like learning how to speak, because with language we are constantly building more complex sentences by being flexible with the words that we have. Number sense is the same, just with numbers. So, it is just a case of learning little strategies which can help build this all-important number sense. Mental math becomes that much easier with these little practical tips, and everyone can do it. 1. Making 9 a 10 10 can be a little tricky because it isn’t a round number. But it is one away from 10. Therefore, any simple math addition or subtraction using nine can be easily adapted so you involve a ten instead, and then you just adapt it accordingly. For example, what is an easier sum to make; 9 + 5 or 10 + 4? Rounding the nine up to ten just means you need to take 1 away from the 5. You can scale up this little technique too as it works with bigger numbers. Think about 99 + 73, for example. Wouldn’t it just be easier to make 100 + 72? This is what being flexible with numbers means. And you can continue to think in terms of compensation related to the nice big round number. So, if 29 is one less that 30, and 48 is two less than 50, and you need to add the two numbers together, how many less that 80 is the answer going to be? 3 of course (=77) 2. Make use of doubles Learning the easy doubles early on can then lead to some nice flexibility. So, start with all of the essential doubles, meaning 1 + 1, 2 + 2 and so on. Once learners have this down, they can then make slightly more difficult additions by adding or subtracting accordingly. Therefore, if 2 + 2 = 4, what is 2 + 3 going to equal? 5, which is 2 + 2 + 1 extra. 8 + 8 = 16. 8 + 7 is one less than 16. That’s number sense as its simple best, and think how that can extrapolate out as the sums get a little more complicated. 3. Perform subtractions by making them additions Using addition skills can really form the basis of all subtractions too, making it one less arduous skill to learn. You simply need to invert the sum. For example, what is 5 – 2 = ? Invert the sum, so now, 2 + ? = 5. Your subtraction is now an addition (the answer is 3 of course). Make the sum a little more difficult. 15 – 7 = ? Is the same as 7 + ? = 15 Or how about 56 – 23 = ? This now becomes 23 + ? = 56? Employ the previous tip of rounding up to ten and you are truly embracing the essence of number sense. 4. The multiplier 5 Now looking at multiplication, the 5 multiplier is a really simple little trick which allows young learners to multiply with more confidence. To understand what 5 x something is, you simply halve the 10 x number. So, if 10 x 9 = 90, then 5 x 9 = 45. Number sense at its best. 5. The multipliers 4 and 8 Sticking with multiplication, this particular little trick is all about doubles. Once you are comfortable with doubling a number, this little multiplication problem becomes much easier. Here’s an example: 2 x 14 = 28. 4 x 14 is the same as 2 x 28. And 8 x 14 is the same as 2 x 56. You are simply being more flexible with those numbers to make the equation easier to solve. 6. Multiply in parts, not wholes This is a simple little technique, and is actually what standard multiplication algorithms are based upon. Instead of multiplying the whole number, break it down to two mutiplications that you can then add together. For example: 4 x 67 = ? Instead of performing the multiplication as a whole, let’s break it down into two easier multiplications. 4 x 60 = 240 4 x 7 = 28 240 + 28 = 268 That number just became a whole lot easier to find.And that’s it. Number sense. It all boils down to staying away from rigidity, and becoming a lot more fluid with these simple equations. Once a young learner becomes comfortable doing that, finding the solution can be become a whole lot easier.