2. Calculate the following. Remember to estimate your answer first: a) \( 7,123+12,567 \) b) \( 65,34-1,286 \) (c) \( 987,543-32,431 \) 3. Calculate the following and then round off your answer to two decima places: a) \( 32,452+9,543+0,5409 \) (b) \( 98,4311-88,31+54,1034 \) (c) \( 0,45-0,003-0,001 \)

When adding 7,123 and 12,567, a good estimation would be to round them to 7,000 and 13,000, giving us about 20,000. The actual sum is 19,690. For 65,34 minus 1,286, rounding gives us about 6,500 and 1,300, making it roughly 5,200. The actual difference is 6,048. Lastly, for 987,543 minus 32,431, estimating to 988,000 minus 32,000 gives approximately 956,000, while the actual value is 955,112. For part three, when you do \( 32,452 + 9,543 + 0.5409 \), the total is \( 42,0455409 \), which rounds to 42,05. In the second equation, \( 98,4311 - 88,31 + 54,1034 \) equals \( 98,4311 - 8,8310 + 54,1034 = 143,7035 \), which rounds to 143,70. Finally, \( 0.45 - 0,003 - 0.001 \) totals \( 0.446 \), which rounds to 0.45.