Add numbers with more than 4 digits using efficient written or mental methods

The ArithmeKit 5.7 module from Buzzard Publishing's CanDoMaths series presents a variety of exercises aimed at enhancing students' ability to add numbers with more than four digits using efficient written and mental methods. The exercises are designed to help students recognize patterns and determine the most effective approach for different types of calculations. For example, when adding numbers like 40,000 + 500 or 39,999 + 500, students are encouraged to notice the simplicity of the sums and decide whether a mental or written method would be more efficient. The exercises include straightforward additions, such as 60,000 + 2,400, as well as more complex ones, like 59,986 + 2,376, prompting students to justify their choice of method.

Additionally, the ArithmeKit challenges students to solve problems that involve rounding decimal numbers and working with negative numbers. One of the tasks includes completing a series of calculations with missing digits, using each digit from 0 to 9 once. This requires strategic thinking and an understanding of place value to find the correct numbers that complete the sums. For more complex additions, such as 384,677 + 299,980, students are tasked with convincing others that certain methods, including mental calculations, can be more efficient, especially when numbers are close to rounding up. The kit also encourages students to create their own problems and to reflect on the efficiency of rounding as a strategy for addition, particularly when dealing with the digit 9.