Rounding 4

Knowing how to round

When the world hears someone rounding, the world makes some assumptions about the number.   If you are going to talk to people, and you want people to understand you, you want to know how to ROUND numbers.   The section explains how people assume you are figuring out the number you used in your comment.

Rounding:

  • People assume that you are giving them a number CLOSE to the number that is accurate.
  • People assume they know what numbers you are using to choose the CLOSE number.

This means that you need to decide what the numbers are that you are going to try to be closest to. Examples:

  • Close to a multiple of 10 ........ 0, 10, 20, 30, 40, 50, 60, 70 ............................. (to the nearest 10)
  • Close to a multiple of 100 ...... 0, 100, 200, 300, 400, 500, 600, 700, 800 ......... (to the nearest 100)
  • Close to a multiple of 1000 .... 0, 1000, 2000, 3000, 4000, 5000, 6000, 7000, .... (to the nearest 1000)
  • Close to a multiple of 1 ........... 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, ........................... (to the nearest whole number)

After deciding which set of numbers you are going to try to be close to, do it .... THINK CLOSE.
THINK CLOSE for the following problems ....

If you were on the block below and you were at house 3416.  
Which end house are you closest to, 3410 or 3420?  
What kind of rounding are you doing?  

   
      3410 3411  3412  3413  3414 3415 3416  3417  3418 3419  3420

If you are at house 321, are you closer to house 300 or house 400?
What kind of rounding are you doing?

   
      300    301    302   ...      320     321   ...       397   398    399   400

You are climbing a mountain.   You are at the 5600 feet level.    
Are you closer to 5000 feet or 6000 feet?   What kind of rounding are you doing?  

You are climbing a mountain.   You are at the 3200 foot level.   
Are you closer to 3000 or 4000 feet?  
What kind of rounding are you doing?  

Check Your Understanding

  1. If you were worried about traveling closest to 3000, 4000 or 5000 miles, 
    what kind of rounding would you be doing? 
  2. If you were worried about being closest to 30000, 40000, or 50000 feet,
    what kind of rounding are you doing?     
  3. If you were worried about things being closest to 90, 100, 110 or 120 ,
    what kind of rounding are you doing?     
  4. Is the following glass closer to full (1 glass) or empty (0 glass). 

(Note: if you are not closest to the smaller amount, we say the larger amount.)