Ted has 18 crayons. Terry has 47 crayons. How many crayons does they have in all?

The correct answer is: 65

Ted has 18 crayons. Terry has 47 crayons.
Total crayon both have = 47 +18
To find partial sums add the digits in tens place and ones place seperately.
Partial sum of 47 + 18
Step 1 : Add digits in tens and ones place seperately:
40                                    07
+ 10                   and        + 08

_____                             ______
50                                        15
Thus, the sum of 47 + 18 are 50 + 15 = 65.

So, they have 65 crayons in all.