Answer key

The answer, and what a wrong answer means.

#	Problem	Answer	If they wrote…
1	8 + 8	16	18 rounding to add, then forgetting to adjust
2	6 + 6	12	no pattern to catch here
3	2 + 1	3	no pattern to catch here
4	2 + 9	11	12 rounding to add, then forgetting to adjust
5	9 + 9	18	19 rounding to add, then forgetting to adjust
6	4 + 3	7	no pattern to catch here
7	7 + 7	14	no pattern to catch here
8	8 + 7	15	no pattern to catch here
9	8 + 8	16	no pattern to catch here
10	5 + 5	10	no pattern to catch here
11	9 + 2	11	12 rounding to add, then forgetting to adjust
12	9 + 1	10	no pattern to catch here
13	7 + 3	10	no pattern to catch here
14	7 + 5	12	no pattern to catch here
15	8 + 4	12	14 rounding to add, then forgetting to adjust
16	5 + 4	9	no pattern to catch here
17	8 + 2	10	no pattern to catch here
18	3 + 3	6	no pattern to catch here
19	7 + 8	15	17 rounding to add, then forgetting to adjust
20	6 + 7	13	no pattern to catch here

Reading the wrong answers

One wrong answer is a slip. The same pattern on three or more problems is a rule your child is following, and it has a name and a fix. Problems marked "no pattern to catch" are the plain ones; a child who gets only those right is telling you something too.

Reading the wrong answers

Rounding to add, then forgetting to adjust 6 of 20 problems