Arithmetic Grade Four

Lesson Fifty-seven: Rounding and Multiplying

Rounding to the Nearest Ten: 

   If the digit in the ones column is 5 or greater, round up.
          
   If the digit in the ones column is 4 or less, round down.

      EXAMPLES:

       88  -->  90	85  -->  90       84  -->  80

     1233  -->  1230    19  -->  20     3335  -->  3340
Here are some problems were we are asked to first round to the nearest ten and then multiply: 

  1)   4321 x 78
       ROUND TO NEAREST TEN: 4320 x 80
       MULTIPLY:  4320 x 80 = 345,600

  2)   775 x 89
       ROUND TO NEAREST TEN: 780 x 90
       MULTIPLY:  780 x 90 = 70,200

You get to try a few for yourself on the next page.

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