Copyright © Cengage Learning. All rights reserved. 8.2 Arithmetic Sequences and Partial Sums.
Adding Partial Sums
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Adding Partial Adding Partial Sums Sums
description
Adding Partial Sums. First you need to do a Ballpark Estimate. 243 + 208. Ballpark Estimate:___________________________________. Remember it’s easier to work with estimating when you only have 0s after the first number. 243 estimated to 2 00 + 208 estimated to 2 00. - PowerPoint PPT Presentation
Transcript of Adding Partial Sums
Adding Partial SumsAdding Partial Sums
First you need to do a Ballpark Estimate
243243
+ 208+ 208
Ballpark Estimate:___________________________________
Remember it’s easier to work with estimating Remember it’s easier to work with estimating when you only have 0s after the first number.when you only have 0s after the first number.
243 243 estimated to estimated to 220000
+ 208 + 208 estimated to estimated to 220000
243 is closer to 200 than is it to 300.
Ballpark Estimate:__200+200=400_________________________
Remember how we expand Remember how we expand numbersnumbers
224433 = = 200 200 + + 40 40 + + 33
+ + 220088 = = 200 200 + + 00 + + 88
Ballpark Estimate:__200+200=400_________________________
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Remember how we expand Remember how we expand numbersnumbers
224433 = = 200200
+ + 220088 = = 200200
Ballpark Estimate:__200+200=400_________________________
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Remember how we expand Remember how we expand numbersnumbers
224433 = = 200 200 + + 4040
+ + 220088 = = 200 200 + + 00
Ballpark Estimate:__200+200=400_________________________
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Remember how we expand Remember how we expand numbersnumbers
224433 = = 200 200 + + 40 40 + + 33
+ + 220088 = = 200 200 + + 00 + + 88
Ballpark Estimate:__200+200=400_________________________
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224433 + + 220088
Ballpark Estimate:__200+200=400_________________________
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= = 200200
+ + 4040
+ + 33
= = 200200
+ + 88
Think: Think: 200200 + + 200200 = = 400400400400
Think: Think: 4040 + + 00 = = 40404040Think: Think: 33 + + 88 = = 11111111
445511
Does my answer make sense? Is it close to my ballpark estimate?
YES!
First, make a First, make a Ballpark estimate.Ballpark estimate.
638638
+ 429+ 429
Ballpark Estimate:___________________________________
Let’s do another oneLet’s do another one
Remember it’s easier to work with estimating Remember it’s easier to work with estimating when you only have 0s after the first number.when you only have 0s after the first number.
638 638 estimated to estimated to 660000
+ 429 + 429 estimated to estimated to 440000
Ballpark Estimate:__600+400=1,000____________
Keep in mind how we expand numbers Keep in mind how we expand numbers so we can do partial sumsso we can do partial sums
663388 = = 600 600 + + 30 30 + + 88
+ + 442299 = = 400 400 + + 2020 + 9 + 9
Ballpark Estimate:__600+400=1,000_________________________
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663388 + + 442299
Ballpark Estimate:__600+400=1,000_________________________
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= = 600600
+ + 3030
+ + 88
= = 400400
+ + 99
Think: Think: 600600 + + 400400 = = 1,0001,0001,0001,000Think: Think: 3030 + + 2020 = = 50505050
Think: Think: 88 + + 99 = = 171717171,1,006677
+ + 2020
Does my answer make sense? Is it close to my ballpark estimate?
YES!
