Doubles Plus 1
Doubles, doubles,
Doubles are fun,
But much better yet,
Are doubles plus 1!
Double a 4,
You always get 8,
Let's memorize that,
'Cause doubles are great!
So 4 + 5,
Is just 1 more!
You gotta' get 9?
Just check to be sure!
4 + 4,
Plus 1,
Is 9,
Doubles plus 1,
Saves you sweet time!!!
Know a double?
Add 1 more!
Doubles plus 1,
The best way to score!
Doubles, doubles,
Doubles are fun,
But much better yet,
Are doubles plus 1!
Watch Mr. R.'s
Doubles + 1 Numbers Music Video 

Watch Mr. R.'s
Double Numbers Music Video 

Math Challenges 
If double 9 (9 + 9) is equal to 18, what is 9 + 10 equal to? 
One friend gives you 7 pieces of candy. A second friend gives you 7 more pieces of candy, and a third friend gives you 1 more piece of candy. How many pieces of candy do you have in total? (remember to add the doubles first!) 
What's 25 + 26 equal to? (think about doubles + 1 to solve quickly!) 

