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- Estimation

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Get Started Now- Intro Lesson: a8:42
- Intro Lesson: b12:12
- Intro Lesson: c2:06
- Intro Lesson: d6:44
- Intro Lesson: e6:52
- Intro Lesson: f6:09
- Lesson: 1a4:17
- Lesson: 1b3:30
- Lesson: 1c4:42
- Lesson: 2a4:41
- Lesson: 2b4:19
- Lesson: 2c9:40
- Lesson: 3a2:02
- Lesson: 3b1:48
- Lesson: 3c2:54
- Lesson: 3d1:57
- Lesson: 410:11
- Lesson: 5a1:23
- Lesson: 5b2:59
- Lesson: 5c3:24
- Lesson: 5d3:16

In this lesson, we will learn:

- How to estimate the answer to addition statements
- The two methods for estimating sums: front-end estimation and estimation by rounding
- How to check and compare your estimated sums with the
**exact answer**

- An
**estimation**is a rough calculation (or guess) of what the**exact answer**could be around. - We use the symbol $\approx$ when estimating; it means “about equal to”
- An estimation is less exact, but it’s easier (faster) to calculate
- When
**estimating**, it is helpful to remember how to**round**numbers - You can round to any place value by:
- Keeping all the bigger place values (to its left) and fill in all the smaller place values (to its right) with zeroes.
- Looking at the number in the smaller place value (to its right).
- If that number is 5 or bigger ($\geq$ 5), round UP.
- If that number is 4 or smaller (< 5), round DOWN. (keep the same value in that digit)
- For a mixed fraction, round to the nearest whole number by looking at the fraction portion. If the fraction is $\geq \frac{1}{2}$ round UP; if the fraction is < $\frac{1}{2}$ round DOWN
- Two methods to estimate
**sums: frond-end estimation and estimation by rounding** **Front-End Estimation:**- The front digit is the greatest place value out of all your addends (ex. only thousands column; only hundreds column)
- Adding mixed fractions: add the whole number parts only
- All the other digits of the answer become zero; skip this step for mixed fractions
- If the back digits can be grouped together to make a group of ten (i.e. one front digit), add to the front digit estimate
- If you are adding mixed fractions, see if the fraction portions can be added to make at least one more whole; if so, add to the estimate
**Estimation by Rounding:**- Round to the greatest place value of the smallest number out of all your addends
- If you are adding mixed fractions, round to the nearest whole number
- You can
**compare**the**exact sum**and the**estimated sum**to see how close they are - An
happens when you round DOWN the addends; the estimated sum is LESS than the exact sum__underestimate__ - An
happens when you round UP the addends; the estimated sum is MORE than the exact sum__overestimate__

1.

1.

- IntroductionIntroduction to Estimating Sums:a)Example of estimating the sum of 1617 + 3898b)How to round mixed fractionsc)Key terms for estimating sumsd)Front-end estimation for sumse)Estimation by Rounding for sumsf)Underestimating and overestimating sums
- 1.
**Front-End Estimation of Sums**

Estimate the sum using front-end estimation. Then, find the exact sum to check your answer.a)6895 + 2413 + 1878 =b)0.835 + 0.02 + 0.66 =c)36$\frac{3}{10}$ + 14$\frac{1}{2}$ + 27 $\frac{2}{5}$ = - 2.
**Estimating Sums by Rounding**

Estimate the sum using estimation by rounding. Then, find the exact sum to check your answera)3128 + 744 + 29 =b)3.78 + 0.94 + 5.261 =c)6$\frac{2}{9}$ + 9$\frac{3}{6}$ + 8$\frac{4}{7}$ + 3$\frac{1}{11}$ = - 3.
**Estimating Sums Word Problem - 1**

A pirate finds a map that shows the route to some treasure. The instructions tell the pirate to go: 25.42 km North, then 61.3 km West, and finally 79.018 km North-East.- About how many kilometers is the entire route to the treasure?

a)Write the addition equation that represents this question.b)Use the front-end estimation method to estimate.c)Use the rounding estimation method to estimate.d)Calculate the exact answer. - 4.
**Estimating Sums Multiple Choice**

Estimate the sum using multiple estimation methods. Then choose the best answer:12$\frac{5}{8}$ + 11$\frac{4}{5}$ =

A. Less than 23

B. Between 23 and 24

C. Greater than 24 - 5.
**Estimating Sums Word Problem - 2**

This week, Elizabeth ran 3$\frac{1}{5}$ miles on the Monday, 7$\frac{3}{4}$ miles on Wednesday, and 5$\frac{3}{8}$ miles on Friday. About how many miles did she run in total for the week?a)Write the addition statement that represents the question.b)Use front-end estimation method to estimate.c)Use the rounding estimation method to estimate.d)Calculate the exact answer.