How many of the whole numbers less than $$100$$ are $$10$$ greater than an odd whole number?　 
Overseas Competition->Knowledge Point->Number Theory Modules->Odd and Even Numbers->Understanding Odd and Even Numbers
Add $$10$$ to $$1$$, $$3$$, $$5$$, $$7$$, $$\cdots $$, $$87$$, and $$89$$. None of these sums is more than $$99$$. There are $$45$$ such sums. 