Mental arithmetic is a teaching method that originated in Asia but is gaining popularity around the world today. It is based on mechanical calculation on abacus, the development of skills of counting mentally and exercises for concentration and logic. Mental arithmetic helps to develop thinking speed and creativity.
Mental arithmetic skills help children better understand basic mathematical concepts. In addition, children develop a sense of self-confidence when they know that they can do calculations mentally, and they do not need a calculator, pen and paper. When a child learns to count mentally, solving simple arithmetic problems will take him less time than if he were counting on a calculator.
In the early stages of learning mathematics, the use of auxiliary tools (such as calculators or counting sticks) helps children understand equations and other mathematical concepts. As soon as the child learns simple concepts, he will be ready to learn mental arithmetic.
Exercises of mental arithmetic
Use the following exercises and calculation methods to help children develop their math skills. With these methods, they will learn to break down mathematical problems into simpler parts and solve them mentally.
The first method of calculation – decomposition – means the representation of numbers in expanded form (tens and ones). This method is well suited for adding two-digit numbers, as it is not difficult for children to divide numbers into tens and ones, as well as to add prime numbers. Example:
25 + 43 = (20 + 5) + (40 + 3) = (20 + 40) + (5 + 3).
It is easy for a child to understand that 20 + 40 = 60, and 5 + 3 = 8, so the overall result will be 68.
Decomposition can also be used to teach a child to subtract mentally. The difference is that the largest number does not need to be decomposed into parts:
57 – 24 = (57 – 20) – 4.
Accordingly, 57 – 20 = 37, and 37 – 4 = 33.
Sometimes it is easier for a child to solve a problem by rounding off one or more numbers. For example, if you want to add 29 + 53, it is easier to round 29 to 30, and then you can easily assume that 30 + 53 = 83. Then you need to subtract the “extra” unit that appeared after rounding. So we get the final result – 82.
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Rounding can also be used for subtraction. For example, if you want to solve an example: 53 – 29, you can round 29 to 30.
53 – 30 = 23.
Then you need to add the unit that remains after rounding, and we get the final result – 24.
Another way to subtract mentally. It is to round the subtractor to ten. Then you need to add tens to get decreasing. You can then calculate the balance.
Consider this method by example:
87 – 36.
To solve the example by adding, you need to add up to 36 numbers until you get 87. First, you can round 36 to 40:
36 + 4 = 40.
Then you need to add tens until you get 80. So we learn that the difference between 36 and 80 is 44
4 + 40 = 44.
Then you need to add to this amount the remaining 7 – the number that is missing to 87:
44 + 7 = 51.
Thus, we obtained the final result: 87 – 36 = 51.
When the child learns to add even numbers (2 + 2, 5 + 5, 8 + 8, etc.), he will be able to use it for mental calculations. When a child is faced with an arithmetic problem close to adding even numbers, he can simply add numbers and then adjust the result.
Example 6 + 7 is close to 6 + 6. The child already knows that 6 + 6 = 12. Then she has to add 1 to get the final answer:
12 + 1 = 13.
Games for mental arithmetic
Show your child that math can be interesting. To do this, you can use active games that are well suited for younger students.
Find the numbers
Write five numbers on the board (for example, 10, 2, 6, 5, 13). Then ask your child to find a number among them that matches the following statements:
The sum of these numbers is 16 (10, 6);
The difference of these numbers is 3 (13, 10);
The sum of these numbers is 13 (2, 6, 5).
Use other sets of numbers and arithmetic operations.
This is an active game, which means that it is sure to appeal to children of primary school age. This game can be played in class. Tell the children, “Form groups of …” and encrypt the number in the example (for example, 10 – 7, which means that the children need to form groups of three). In the course of the game you can complicate the task, for example, 29 – 17 (children should unite in groups of 12 people).
Get up / sit down
Before giving the children a task, ask them to stand if the answer is greater than a certain number, and to sit down if it is less. For example, children should get up if the answer is greater than 25 and sit down if the answer is less. Then voice the task: 57 – 31. If the children solve the problem correctly several times in a row, you can complicate the examples. Change the number that is the reference point.
Game with a date
Write the date on the board every morning. Invite the children to come up with an example that will answer this number. For example, if the date is December 8, children can offer the following examples: 4 + 4, 5 + 3, 10 – 2, 18 – 10, 6 + 2.
Older children can offer examples of addition, subtraction, multiplication and division.
Divide the children into two teams. Draw a square on the board or arrange tables in the shape of a square. Take turns giving examples to members of both teams. For each correct answer, the child moves to the next corner of the square. After the participant gives 4 correct answers and passes all the corners, he passes the baton to the next participant.