evaluating for a number

I apologize for the simple question but can someone please help me with how to evaluate a number?

I will be reading in a file and if a number is >= 100000000, I will do something, if not, I will exit the if statement.

Thanks in advance

the syntax is different from shell to shell and language to language.
c syntax would look like:

if (x >= 100000000)
{ 
cout>>" do something ";
}

bash would look like:

if [ $somevar -ge whatever  ]
then
do something 

oh yah, in bash you can also do it like:


if (( "$somevar" >= "$somethingelse" ))
then
the rest