3rd Grade Estimating Sums in Stories Worksheet: Round, Then Add

An estimate gives a quick answer that is close to the exact one. This 3rd grade estimating sums in stories worksheet has three word problems, numbered 1 to 3. In the first, Paul, Kevin and Boris collect seashells on the beach. In the second, Nancy adds pencils to a drawer, and in the third, Mike harvests watermelons over two years. Each problem names the place to round to, either the nearest ten or the nearest hundred, so your child rounds every number first and then adds. Two children with shells and a boy on watermelons decorate the page. Page two writes out every step in pink.

Round first, then add

The estimated sums are 2,400 seashells, 450 pencils and 18,200 watermelons. In problem 1, Paul has 587 shells, Kevin has 587 × 2 = 1,174 and Boris has 587 − 27 = 560. So the sum rounds to 600 + 1,200 + 600 = 2,400. In problem 2, 346 rounds to 350 and 99 rounds to 100, which gives 450.

Problem 3 rounds 9,927 to 9,900 and 8,296 to 8,300, so the estimate is 18,200. However, these 4-digit numbers go past the third grade target of 1,000. Problem 1 also needs 587 × 2 before any rounding, so help your child with those steps, or let them use the key as a model.

At the table: say the rounding rule

Before each sum, ask your child which digit decides the rounding. For the nearest hundred, it is the tens digit, so 587 has an 8 and goes up to 600. Then they write the rounded numbers in a row and add them, and as a result, the hard part becomes easy mental math. This rounding rule works for every problem on the page.

The text has a few slips worth fixing. Problem 3 says "from is large watermelon farm" instead of "from his". Problem 1 says "27 seashells less than Paul", but "fewer" is the right word. In the key, problem 2 ends with "in the drawer row" for "now", and 18, 200 has a stray space.

After the page: the game score

Write two scores from a game, such as 48 and 73 points. Your child rounds each one to the nearest ten and adds: 50 + 70 = 120. Then they add the exact scores, 121, and compare. In the end, check the three answers with the answer key on page two.