Starting at 0 we can count up in 10s like this:

 

0    10    20    30    40    50    60    70 ...

 

Example

When we count up in 10s, what comes before and after 50?

 

30    40    50    60

 

Answer

40 comes before.  60 comes after.

 

When we start at 6, the numbers go up in 10s like this:

 

6    16    26    36    46    56    66    76    86 ...

 

Did you notice that only the number in the tens column changes when you add or subtract 10?

 

Example

When we count up in 10s, what comes before 57?

 

17    27    37    47    57    67    77    87

 

Answer

47

 

Does that make sense? 
 

 

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