distributive property
One way is to do front end estimation!
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
An article on cost estimating in the building construction field, admittedly from an out dated source although the principles are still the same, is at http://www.inquirewithin.biz/Vol2/Estimating/estimating_foundations.htm.
It means to round a number to the nearest whole number, tens, hundreds, etc.
Alike is the same as Differences means subtractions Sums means additions Quotients means divisions Products means multiplications
distributive property
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.
When estimating sums, it is best to round to the nearest round number. If the last place on the right is less than 5, then round down. If the last place on the right is 5 or more, then round up. For example, 43+88. You would round the 43 down to 40 and the 88 up to 90. The estimated sum would 130.
In the same way as you estimate them for whole numbers.
One way is to do front end estimation!
0.7 + 0.9 = 1.6 0.7 - 0.9 = -0.2
Find your number, look Right next door, five or more just add one more, four or less just ignore...
When you do not require an exact answer but an approximation is sufficient.
It means to give the reason of something, (numbers,sums,differences, and problems.)
150 - 4000 - 600 = -4450