Max Maths, Year 5, Try it, Adding and subtracting near multiples of 10 and 100 (1)

In a Year 5 mathematics exercise from Max Maths, students are presented with a practical approach to subtracting near multiples of 10 and 100. The first problem asks the student to calculate 458 minus 99. To simplify the process, the student is encouraged to consider 99 as being close to 100 and to count back in tens from 458. The sequence provided on the page helps visualise this process. After subtracting 100, the student realises that they have subtracted one too many, and thus, they need to add 1 back to the result. This step-by-step method helps students understand the concept of adjusting their calculations when dealing with near multiples.

The second problem involves subtracting 18 from 65, where students apply a similar strategy. Since 18 is close to 20, they count back in tens twice to simplify the subtraction. The provided number line aids in visualising the subtraction of 20 from 65, resulting in 45. However, since the actual number to subtract is 18, the student realises they have subtracted 2 too many. To correct this, they add 2 back to 45. This exercise reinforces the technique of breaking down subtraction problems into more manageable chunks and adjusting the result when subtracting numbers that are close to multiples of 10.