Max Maths, Year 5, Practice, Multiplying by 19 or 21 mentally

In the "Max Maths" practice exercises for Year 5, students are encouraged to multiply numbers by 19 or 21 using mental arithmetic. The "Let's Try It" section presents a series of multiplication problems that require students to apply strategies for mental calculation. For instance, when multiplying by 19, a useful technique might be to multiply by 20 (a simpler task) and then subtract the original number. Similarly, for multiplying by 21, one could multiply by 20 and then add the original number. The exercises are designed to help students become more comfortable with these near-base multiplication problems, enhancing their mental math skills.

The "Let's Practise" portion of the exercise further challenges students to multiply numbers mentally, asking them to demonstrate their thought process. Here, students might use the same strategies as before, multiplying by 20 and then adding or subtracting the original number accordingly. For example, to find 19 × 7, students might calculate 20 × 7 and then subtract 7 from the result. These exercises not only reinforce the students' multiplication skills but also encourage them to develop and refine their mental arithmetic techniques. Students are then directed to workbook pages 75 to 76 for additional practice and to consolidate their learning.