Objective: Estimate sums by rounding and apply to solve

measurement word problems.Lesson 17

Addends- The numbers that are being added together.

Reasonable- Does it make sense?

Vocabulary

First we find the nearest hundred. 362 ~ 400 159~200

Then we round to the nearest ten. 362~ 360 159~ 160

Then we round to the closest 50. 360~350 159~150

Estimate the sum of 362+159 by rounding.

362 + 159

400 + 200 = 600 (Rounding to nearest hundred)

360 + 160 = 520 (Rounding to nearest ten)350 + 150= 500 (Rounding to nearest 50)

Which method of rounding will give the closest sum?

Talk to your neighbor about your answer.

Using Rounding to Find the Sum

(A) 349 + 145 (B) 352 +145 (C) 352 + 151

Round to the nearest hundred Round to the nearest ten Round to the nearest 50

What did you realize about these numbers? Find the exact value of the sums.

Round these numbers all 3 ways

296 + 609 Round to the nearest hundred Round to the nearest ten Round to the nearest 50

What did you realize about these numbers? Find the exact value of the sums.

Round and analyze the sum