Add and Subtract 10, 100 and 1,000 using Place Value

Using place value, you can add or subtract 10 to a number, or even 100, or EVEN 1,000, pretty easily, just by thinking about the expanded value of the number. 

e.g. 6,578 + 10                          or + 100                                   or + 4,000 

Let's expand it first:
6,000 + 500 + 70 + 8          6,000 + 500 + 70 + 8               6,000 + 500 + 70 + 8 
                    + 10                        + 100                           + 4,000 
= 6,000 + 500 + 80 + 8    = 6,000 + 600 + 80 + 8          =10,000 + 500 + 80 + 8 
= 6,588                                     = 6,688                                   = 10,588 


What a cool trick!