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 + 8	15	17 rounding to add, then forgetting to adjust
3	9 + 4	13	14 rounding to add, then forgetting to adjust
4	2 + 6	8	no pattern to catch here
5	3 + 2	5	no pattern to catch here
6	7 + 3	10	no pattern to catch here
7	5 + 5	10	no pattern to catch here
8	2 + 2	4	no pattern to catch here
9	8 + 8	16	18 rounding to add, then forgetting to adjust
10	3 + 7	10	no pattern to catch here
11	9 + 8	17	no pattern to catch here
12	8 + 9	17	18 rounding to add, then forgetting to adjust
13	4 + 7	11	no pattern to catch here
14	7 + 9	16	17 rounding to add, then forgetting to adjust
15	7 + 7	14	no pattern to catch here
16	9 + 7	16	17 rounding to add, then forgetting to adjust
17	6 + 7	13	no pattern to catch here
18	8 + 4	12	14 rounding to add, then forgetting to adjust
19	9 + 9	18	no pattern to catch here
20	8 + 7	15	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 8 of 20 problems