Mental Math
True or False:
When adding, I can use the commutative property to add in any order.
For example, 24+45=35+24
True
Estimate to the highest place value, then solve.
2,189+1,388
3,000
72,314+35,525=
107,839
6,794-1,058
5,736
How can you use the associative property to solve 204+489+126?
(204+489)+126
(489+126)+204
{add 2 numbers then add the total to the last number}
Estimate to the highest place value, then solve.
65,327-14,231
60,000
14,312 + 9,617
23,929
215,714 - 176,313
39,401
True or false
It does not matter which number is on top when subtracting.
False
The larger number goes on top
Estimate to the ten-thousands place, then solve.
184,321 + 138,941=
180,000 + 140,000=
320,000
30,080 + 19,187
49,267
85,968 - 74,084
11,884
The answer to an addition problem is called?
Sum
Estimate to the thousands place, then solve.
468,127 - 265,834=
468,000-266,000=
202,000
29,634 + 12,958 + 6,835
49,427
726,003 - 282,942
443,061
The answer to a subtraction problem is called
Difference
Estimate to the highest place, then solve.
98,633 + 42,997
100,000 + 40,000=
140,000
64,673 + 48,262 + 298,918=
411,853
Solve, then show the inverse operation to check your work.
6,000 - 1773
4,227
--------
4,227 + 1,773 = 6,000