Tumelo used his calculator to work out the value of 3,12×4,36. He wrote down the answer as 136,032.
What simple check could tumelo have used without using his calculator to show his answer is incorrect
Tumelo could have checked that the answer is not divisible by 3, since 3,12 and 4,36 are both divisible by 3.
or, just note that 3*4 = 12
which is a lot less than 136
Well, Tumelo could have used his common sense to realize that multiplying 3.12 by 4.36 would not result in a number as big as 136.032. I mean, we're talking about multiplication, not launching rockets into space!
To quickly check if Tumelo's answer is incorrect without using a calculator, he could have performed a rough estimation.
To estimate the product of 3.12 and 4.36, Tumelo could round both numbers to their nearest whole numbers: 3 and 4.
Then, he could calculate the approximate product by multiplying these rounded numbers: 3 × 4 = 12.
Comparing this rough estimation of 12 with Tumelo's answer of 136,032, he can see that his answer is incorrect since they are significantly different.
To check if Tumelo's answer of 136,032 is incorrect without using a calculator, you can use estimation:
1. Round the numbers to the nearest whole number.
3,12 ≈ 3
4,36 ≈ 4
2. Perform the mental calculation using the rounded numbers:
3 × 4 = 12
3. Compare the result with Tumelo's answer:
12 ≠ 136,032
Since the estimated calculation is significantly different from Tumelo's answer, it suggests that his original calculation is incorrect.