How to use pcall?

I want to protect my calls in case something goes wrong the whole game wouldn't be broken, but how do I get the results from the functions? For example:

function randomstuff()
a = pcall(math.random,1,100)
if a then
 print([The result])
else return false
end
end

How would I get the results from the pcall?

A more pratical use would be:

function safeaddvalue(parent,name,value,add)
	a = pcall(value.Value = value.Value + add)
	if not a then
		b = Instance.new("NumberValue",parent)
		b.name = name
		b.value = add
		return false
	else return true
	end
end

My temporary solution:

function randomstuff()
	a = pcall(b = math.random,1,100)
	if a then
 		print(b)
	else return false
	end
end

Is it the correct way to do it? if not, what is?