Compatible numbers are the numbers that are easy to add, subtract, multiply, or divide mentally (in your head).
Rounded numbers are an integer that ends with one or more "0"s.
Which box below represents compatible numbers and which box below represents rounded numbers?
Which method of estimation do you think is easier, compatible numbers or rounded numbers? Why?
Sentence Stem (type in a complete sentense):
I think the easier method of estimation is to use ______________________ because ___________________________________________.
Vocabulary
compatible numbers approximate round
rounded numbers estimate add/ subtract
Lilly has 37 sun dresses and 23 formal dresses. To find about how many dresses she has all together, she wrote 40 + 20. Which best describes the method of estimation used by Lilly.
Terrell has 64 movie DVDs and 37 sports DVDs. To find the approximate difference in the two numbers, he wrote 65 − 35. Which best describes the method of estimation used by Terrell.
Marty has two ant farms. One ant farm has 327 red ants and the other ant farm has 512 black ants. To find his estimated total, Marty wrote 300 + 500. Which best describes the method of estimation used by Marty.
Rounding to nearest 10
Rounding to nearest 100
Using compatible numbers
Millie sold 27 boxes of Thin Mints girl scout cookies and 42 boxes of Peanut Butter Patties. About how many more boxes of Peanut Butter Patties did Millie sell than Thin Mints?
Nate's father asks him to research the cost of a new laptop computer and printer. He finds a new laptop for $455 and a printer for $142. What amount should Nate tell his father if he rounds both prices to the nearest $10?