Estimate each of the following and then use a calculator to find the actual answer:
a: 343+ -42 - 402
b: -1992 + 3005 - 497
c: 992 - -10,003 - 101
d: -301 - -1303 + 4993
What are your estimates?
343+ -42 - 402
My estimate is -102
Actual answer = -101
I'll be glad to check your answers.
That is what I had for the first one. Wanted to make sure I was doing it correctly.
Don't worry too much if your estimate is far different from the actual answer. We learn by making mistakes. :-)
To estimate each of the given expressions, we can round the numbers to the nearest hundred, thousand, or any other significant place value. Then, we can use a calculator to find the exact answers.
a: 343 + (-42) - 402
We can estimate each number by rounding them to the nearest ten:
Round: 340 + (-40) - 400
Using a calculator, the exact answer is:
Exact: 343 + (-42) - 402 = -101
b: -1992 + 3005 - 497
We can estimate each number by rounding them to the nearest hundred:
Round: -2000 + 3000 - 500
Using a calculator, the exact answer is:
Exact: -1992 + 3005 - 497 = 516
c: 992 - (-10,003) - 101
We can estimate each number by rounding them to the nearest thousand:
Round: 1000 - (-10,000) - 100
Using a calculator, the exact answer is:
Exact: 992 - (-10,003) - 101 = 9,996
d: -301 - (-1303) + 4993
We can estimate each number by rounding them to the nearest hundred:
Round: -300 - (-1300) + 5000
Using a calculator, the exact answer is:
Exact: -301 - (-1303) + 4993 = 5,989
It's important to note that estimations may not always provide the exact answer, but they are useful for getting a rough idea of the result before using a calculator for precise calculations.