Once can roughly round to tens if the numbers are less than 1000, or to hundreds if the numbers are less than 10000, etc., trying to make up for large round-off errors which occur when the number are close to 1/2 the round-off amount.
E.G Add: 13+ 57+ 49 + 45 + 78 + 105
Add 10 + 60 +50 + 50 + 80 + 100
One way is to do front end estimation!
xxx=2x
distributive property
Using only sums and differences, and not necessarily all four numbers, 1, 3, 9 and 27 will make all numbers from 0 to 40.
To give a reason to something,(numbers, sums, differences, or problems you usle hear the word reasonablein a map scale problem like me
In the same way as you estimate them for whole numbers.
The basic idea is the same as when you estimate sums and differences of larger numbers (which may or may not be integers). You round the numbers to one or two decimal digits, then add them up.
One way is to do front end estimation!
0.7 + 0.9 = 1.6 0.7 - 0.9 = -0.2
When you do not require an exact answer but an approximation is sufficient.
150 - 4000 - 600 = -4450
xxx=2x
you have to add
Alike is the same as Differences means subtractions Sums means additions Quotients means divisions Products means multiplications
distributive property
I think you round it to the nearest whole number...
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