Max Maths, Year 5, Learn together, Multiplying by 25 mentally

Max Maths Year 5 introduces a mental strategy for multiplying numbers by 25, making the process simpler and more accessible for young learners. To illustrate this, let's consider the example of multiplying 25 by 16. Instead of calculating directly, the method involves two straightforward steps. First, we multiply the number by 100, which is easily done by adding two zeros to the end of the number. So, for 16 multiplied by 100, we get 1600. Next, since 100 is four times larger than 25, we need to find one quarter of our result. This is done by dividing by 4, which can be further simplified by halving the number twice. Halving 1600 gives us 800, and halving again yields 400. Thus, 25 multiplied by 16 equals 400.

Another example is multiplying 6 by 25. Following the same method, we first multiply 6 by 100, resulting in 600. To adjust for the difference between multiplying by 100 and by 25, we then divide 600 by 4. This step can be mentally calculated by dividing 600 in half to get 300, and then halving 300 to reach 150. Therefore, 6 times 25 is equal to 150. This technique, which involves multiplying by 100 and then finding a quarter of the result, simplifies the process of multiplying any number by 25 and can be easily applied to various numbers for quick mental calculations.