Simple games and tricks you can use to develop your child’s mental arithmetic skills in time word problems.
Mental arithmetic is a teaching method that originated in Asian countries, but is now gaining popularity all over the world. It is based on mechanical counting, development of mental counting skills and concentration and logic exercises. Mental arithmetic helps to develop thinking speed and creativity.
Mental arithmetic skills including knowledge what time will it be in one hour help children better understand basic math concepts. In addition, children get a sense of self-confidence when they know they can do calculations in their mind and don’t need a calculator, pen, and paper to do so. When a child learns to count in their head, solving simple arithmetic problems will take them less time than if they were counting on a calculator.
In the early stages of learning math, using assistive tools (such as counting or counting sticks) helps children understand equals and other math concepts. Once a child grasps the simplest concepts, he or she is ready to learn mental arithmetic.
Activities in mental arithmetic
Use the exercises and ways of calculating below to help children develop their math skills. With these ways, they will learn to break math problems down into simpler parts and solve them in their minds.
Decomposition
The first way of calculating, decomposition, means representing numbers in expanded form (tens and ones). This method is good for adding two-digit numbers because children have no trouble breaking numbers into tens and ones, and adding prime numbers. For example:
25 + 43 = (20 + 5) + (40 + 3) = (20 + 40) + (5 + 3).
It is easy for a child to understand identifying shapes and that 20 + 40 = 60 and 5 + 3 = 8, so the total result is 68.
The decomposition can also be used to teach a child to subtract in their mind. The difference is that the largest number does not need to be decomposed:
57 – 24 = (57 – 20) – 4.
Accordingly, 57 – 20 = 37, and 37 – 4 = 33.
Rounding
Sometimes it is easier for a child to solve a problem if they round one or more numbers. For example, if you add up 29+53, it is easier to round 29 to 30, and then you can easily count that 30+53=83. After that, subtract the “extra” unit that appeared after rounding. The final result is 82.
Rounding can also be used for subtraction. For example, if you want to solve an example: 53 – 29, we can round 29 to 30.
53 – 30 = 23.
Then add the one that was left after rounding, and we get the final result, 24.
Adding
Another way of subtracting in the mind. It consists of rounding the subtraction to a tenth. Then we have to add the tens to get the subtractor. After this you can calculate the remainder.
Consider this method using an example:
87 – 36.
To solve the example using the addition method, you must add numbers to 36 until you get 87. First, you can round 36 to 40:
36 + 4 = 40.
Then we add the tens until we get 80. Thus we find out that the difference between 36 and 80 is 44
4 + 40 = 44.
Then we need to add the remaining 7, the number that is missing to 87, to this sum:
44 + 7 = 51.
Thus, we get the final result: 87 – 36 = 51.
Pair numbers.
When a child learns the addition of paired numbers (2 + 2, 5 + 5, 8 + 8, etc.), he can use it to do calculations in his mind. When a child is faced with an arithmetic problem close to pair number addition, he can simply add the numbers and then correct the result.
For example:
the example 6 +7 is close to 6 + 6. The child already knows that 6 + 6 = 12. He then has to add 1 to get the final answer:
12 + 1 = 13.
Games for mental arithmetic
Show your child that math can be fun. To do this, you can use active games that work well for younger students.
Find the numbers
Write five numbers on the board (e.g., 10, 2, 6, 5, 13). Then ask the child to find a number among them that corresponds to 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.
Groups
This is an active game, which means it is sure to appeal to elementary school age children. This game can be played in the classroom. Tell the children, “Group in groups of…” and code the number in the example (e.g., 10 – 7, which means the children need to be in groups of three). As the game progresses, you can make the tasks more difficult, e.g. 29 – 17 (children should group together in groups of 12).
Stand/Sit.
Before asking the children the problem, ask them to stand if the answer is more than a certain number, and to sit if less. For example, children should stand if the answer is more than 25 and sit if the answer is less. Then call out the problem: 57 – 31. If the children get the problem right several times in a row, you may want to make it more difficult. Change the number that is the starting point.
Play with the date.
Write the date on the board each morning. Have the children think of an example to which that number is the answer. For example, if the date is December 8, the children might suggest these examples: 4 + 4, 5 + 3, 10 – 2, 18 – 10, 6 + 2.
Older children can suggest examples for addition, subtraction, multiplication and division.
Square .
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, a child advances to the next corner of the square. After a participant gives 4 correct answers and passes all the corners, he passes the baton to the next participant.
