Answer :
Final answer:
The student is asked to perform some mental calculations. For 99+54, this can be simplified to 153. For 244×99, it can be seen as 244x100-244 = 24156. Question parts c. 99.6 and d.99.15 seem incomplete as there's no operation present.
Explanation:
To perform these mental calculations: a. 99+54, you can add the tens first (90 + 50 = 140), then the units (9 + 4 = 13), and finally add these two results together (140 + 13 = 153).
For b. 244×99, you can think of it as 244x100-244 which equals, 24400-244, so the answer is 24156.
For c. 99.6, this appears to be a prompt with no operation to perform.
As for d.99.15, this also appears like a prompt with no operation.
Remember, when dealing with mentally adding numbers, it's a good strategy to break them down to simpler forms. Multiplying by 99 is almost the same as multiplying by 100 and subtracting the original number.
Learn more about Mental Calculations here:
https://brainly.com/question/37195701
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