Answer :
Final answer:
To estimate the result of 172.98 - 128.301 by rounding, round each number to the nearest whole number before subtracting, giving us 173 - 128, which equals 45. This estimation process utilizes rounding principles and regards to significant figures.
Explanation:
To estimate by rounding the result of 172.98 - 128.301, we should round each number to the nearest whole number before performing the subtraction. The number 172.98 can be rounded to 173 because 0.98 is closer to 1 than to 0. Similarly, 128.301 can be rounded to 128 because 0.301 is closer to 0 than to 1. Now, we subtract the rounded numbers: 173 - 128 equals 45.
Following the rules of significant figures, the presence of numbers after the decimal in the original problem indicates that precision is important, but since we are estimating, we round to whole numbers. It is also important to note that when rounding, if the digit to the right of the target position is 5 or more, we round up. If it's less than 5, we round down. In conclusion, the estimated result of the subtraction after rounding is 45. This process demonstrates the concept of rounding and its application in basic arithmetic operations such as subtraction.
