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Adding Partial Sums

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.

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Adding Partial Sums

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  1. Adding Partial Sums

  2. First you need to do a Ballpark Estimate 243 + 208 Ballpark Estimate:___________________________________

  3. Remember it’s easier to work with estimating when you only have 0s after the first number. 243  estimated to 200 + 208  estimated to 200 243 is closer to 200 than is it to 300. Ballpark Estimate:__200+200=400_________________________

  4. Remember how we expand numbers 243= 200 + 40 + 3 + 208= 200 + 0 + 8 Hundreds Tens Ones Ballpark Estimate:__200+200=400_________________________

  5. Remember how we expand numbers 243= 200 + 208= 200 Hundreds Tens Ones Ballpark Estimate:__200+200=400_________________________

  6. Remember how we expand numbers 243= 200 + 40 + 208= 200 + 0 Hundreds Tens Ones Ballpark Estimate:__200+200=400_________________________

  7. Remember how we expand numbers 243= 200 + 40 + 3 + 208= 200 + 0 + 8 Hundreds Tens Ones Ballpark Estimate:__200+200=400_________________________

  8. Hundreds Tens Ones 243 + 208 + 3 + 40 = 200 + 8 = 200 400 Think: 200 + 200 = 400 40 Think: 40 + 0 = 40 11 Think: 3 + 8 = 11 Does my answer make sense? Is it close to my ballpark estimate? 451 YES! Ballpark Estimate:__200+200=400_________________________

  9. First, make a Ballpark estimate. Let’s do another one 638 + 429 Ballpark Estimate:___________________________________

  10. Remember it’s easier to work with estimating when you only have 0s after the first number. 638  estimated to 600 + 429  estimated to 400 Ballpark Estimate:__600+400=1,000____________

  11. Keep in mind how we expand numbers so we can do partial sums 638= 600 + 30 + 8 + 429= 400 + 20 + 9 Hundreds Tens Ones Ballpark Estimate:__600+400=1,000_________________________

  12. Hundreds Tens Ones 638 + 429 + 8 + 30 = 600 + 20 + 9 = 400 1,000 Think: 600 + 400 = 1,000 50 Think: 30 + 20 = 50 17 Think: 8 + 9 = 17 Does my answer make sense? Is it close to my ballpark estimate? 1,067 YES! Ballpark Estimate:__600+400=1,000_________________________

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