16 / 3
You could use 250 and 750.
I would use 40 for the 38 and 50 for the 51. 90 would be my estimate.
805 and 1/ 3rd
You could use a demand chart to estimate this.
how you would use the scale in miles to estimate to total area of Madagascar
The answer depends on what you want to use the estimate for. If it is being added to 1 billion, I would estimate it as 0. If adding to 25000, I would estimate it as 15000 and if adding to 0.075, I would leave it as it is.
The front end estimate is 600. But estimating a single number, in isolation and without context, is a complete waste of time. If I had to add 558 to 1 trillion, I would estimate it as 0. If I had to add 558 to 0.0000000001, I would use the number as given - not use an estimate.Also, if I had to divide 558 by 5, I would estimate it as 560 since 560/5 = 112 whereas if I had to divide it by 30 I would go for 570 since 570/30 = 19.
You would use water displacement (ie volume)
5.6261
The front end estimate is 800.However, if I needed to add 750 to 1 billion, I would estimate 750 by 0 while if I wanted to add 750 to 0.001, I would use 750 as it is - not an estimate.
The front end estimate is 30. But estimating a single number, in isolation and without context, is a complete waste of time. If I had to add 33 to 1 trillion, I would estimate it as 0. If I had to add 33 to 0.0000000001, I would use the number as given - not use an estimate. Also, for multiplication, I might estimate it by 33.33... and then use 100/3 for calculations.
No because you would not use it as an estimate.