Maths help

[niadainud]

I'm totally stumped by what I'm doing wrong here. I thought I understood how to do these, but my answers for a) and b) are not being accepted. I'm even more stumped by the fact that my answer for question c) is apparently correct and I'm sure I'm approaching them all in the same way. Please help!!

Did you mean to attach a picture or something?

Help with what?

It was there when I pressed Post...

Ok, not sure why it keeps disappearing. I'm just going to type out the questions.

By rounding to one significant figure, estimate the answers to these questions:

a) 24 x 65
0.37

b) 71 x 8.2
0.22

c) 49.3 x 11.1
0.05

Oh FFS. b) and c) are supposed to be in the same format as a) - two numbers multiplied together, then divided by the number underneath.

For a, rounding to 1sf should give you:
20 X 70 / 0.4

0.4 is 2/5, so overall you have
20 X 70 X 5 / 2
10 X 70 X 5
50 X 70
Which is 3500

Does that work?

What are your answers?

I'd do:

a) (24 x 65)/0.37 is (20 x 70)/0.4, which is 1400/0.4, which is 14,000/4 giving 3500

b) (71 x 8.2)/0.22 is (70 x 8)/0.2, which is 560/0.2, which is 5600/2 giving 2800

c) (49.3 x 11.1)/0.05 is (50 x 10)/0.05, which is 500/0.05, which is 50,000/5 giving 10,000

@SilenceInside is correct. These answers are supposed to be estimated by rounding to one significant figure (so the most valuable digit in the number - the number 123456 would be rounded to the nearest hundred thousand so it would become 100,000) and then calculating.

Ah, I think I know where I've gone wrong. I was rounding the answer to 1sf but I should have been doing it for the numbers in the calculations.

You've got it!