Grade 4 - Progress in Mathematics

Clustering

Day Miles

Sunday 432

Monday 396

Tuesday 394

Wednesday 402

Tommy kept a record of his

family’s daily mileage on

a car trip to Mexico.

About how many miles long

was the trip?

When a number of addends “cluster” around

a certain number, an estimate for the sum

may be obtained by multiplying that number

by the number of addends.

Estimate: 432 396  394  402

400  400  400  400

4 
 400  1600

The trip was about 1600 miles long.

Estimate the total by clustering.

1. 37  41  43  35 2. 85  98  87  88


2. 105  98  96 4. 510  483  503


3. 326  289  301  313 6. 740  675  690  727


4. 2943  3201  3065 8. 5624  4875  5133


5. In Elmsford’s schools, East 10. VideoLand rented out 199
   has 489 students, Central movies on Friday, 248
   has 535 students, and West movies on Saturday, and 218
   has 492 students. About how movies on Sunday. About how
   many students are in Elmsford? many movies was this?

estimate

sum

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