Answer key

The answer, and what a wrong answer means.

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