Question

5 a Copy and complete the table, clearly

showing the mental method you would
use to work out each calculation.
b Compare your answers with a partner.
Discuss the questions where you used
different methods.
Calculation
8 x 19
7 x 21
13 x 15
156 + 4
16 x 19
12 x 34
31 x 6
90+1
9 x 30
11 x 15
Method I would use
Work out 8 x 20. Subtract 8.

Answer 1

The question deals with applying mental math strategies to perform various calculations. Methods include adjusting factors for easier calculation, breaking down problems into simpler parts, and applying multiplication rules for adding zeros.

Step-by-step explanation:

The question relates to Mathematics and involves completing a table with mental methods used for various calculations. For each calculation, an appropriate mental math strategy is considered to simplify the process.

1. 8 x 19: Work out 8 x 20, which is 160, and then subtract 8 to get 152.
2. 7 x 21: Recognize that 21 is 7 x 3, so 7 x 21 is the same as 7 x 7 x 3. Calculate 49 (7 x 7) and then multiply by 3 to get 147.
3. 13 x 15: Break down the multiplication into 10 x 15 + 3 x 15, which equals 150 + 45, resulting in 195.
4. 156 + 4: Simply add 4 to 156 to get 160.
5. 16 x 19: Multiply 16 by 20 to get 320, then subtract 16 for the extra 1 in 19, resulting in 304.
6. 12 x 34: Multiply 12 by 30 to get 360, then add the result of 12 x 4, which is 48, to end up with 408.
7. 31 x 6: Multiply 30 by 6 to get 180, then add 6 for the additional 1, resulting in 186.
8. 90 + 1: Straightforward addition to get 91.
9. 9 x 30: Recognise that this is the same as 9 x 3 followed by adding a zero, resulting in 270.
10. 11 x 15: Recognize that 11 is just 10 + 1, so calculate 10 x 15 and add 15, resulting in 150 + 15, which is 165.