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Exercises Numbers, fractions and percents

Example 1.16 from Prealgebra, 1.2 Add Whole Numbers

Add Whole Numbers: example 1.16

Add:

ⓐ $8 + 7$
ⓑ $7 + 8$

Work it out on paper first. Then open the solution one step at a time, and stop as soon as you can finish on your own.

1
Solution
- ⓐ
  
  Add. $8 + 7$
  
  $15$
- ⓑ
  
  Add. $7 + 8$
  
  $15$
Did you notice that changing the order of the addends did not change their sum? We could have immediately known the sum from part ⓑ just by recognizing that the addends were the same as in part ⓑ, but in the reverse order. As a result, both sums are the same.

Your turn

The book's Try It right after this example: same idea, new numbers. Only the answer is given.

Add: $9 + 7$ and $7 + 9 .$

How did it go?

PreviousAdd Whole Numbers: example 1.15 Next Add Whole Numbers: example 1.17

From Prealgebra (1st edition) by OpenStax (Rice University), section 1.2, licensed under CC BY 4.0. Original at openstax.org. We split the solution into steps; the words, numbers and figures are the book's. OpenStax doesn't endorse this site.