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Rounding Numbers. What is rounding and why do we need to round?. Rounding numbers means finding the closest number that is easier to work with when you need to add or subtract multiple numbers.
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What is rounding and why do we need to round? • Rounding numbers means finding the closest number that is easier to work with when you need to add or subtract multiple numbers. • For example, when your parents go to the store, they can’t add $4.99, $3.89, and $8.99 in their heads. Instead, they round each amount to the nearest dollar. So, • $4.99 becomes $5.00 • $3.89 becomes $4.00 • $8.99 becomes $9.00 These amounts are much easier to add in your head. they can expect the total to be around $18.00.
More Real Life Examples • Sara gets paid $5.85 for each lawn she mows. If she mows 5 lawns, about how much money will she make? What amount is close to $5.75 that would be easier to work with? • $5.85 can be rounded to $6.00. $6.00 x 5 = $30.00, so Sara will be making about $30.00. • Blake is setting up a soccer tournament and needs to make sure he has enough water bottles for all the players. If Team A has 17 players, Team B has 22 players, and Team 18 players, about how many water bottles does he need to buy?
Rounding Steps • Look at the number to the right of the underlined digit, then decide whether you’ll need to round “up” or “down”. • If you have to round up, the underlined digit will increase by one. • If you have to round down, the underlined digit will stay the same.
Practice • Round the numbers below to the underlined place in your math notebooks: • 789 • 5,345 • 3,497 • 756,494 • 1,324,578 • 2,548,367 • **Bonus** 9,999,999
