Adding together numbers in which the addends are greater than 9 can be more difficult to do without a piece of paper to work out the problem. When adding numbers greater than 9 it is best to start out by lining up the numbers so that the place values match up vertically.
Example:
45
+32
Starting with the one's column, add the numbers together, in this case 5+2:
45
+32
7
Next add the tens column together; in this case 4 + 3:
45
+32
77
Finally you arrive at your answer of 77.