Answer key

The answer, and what a wrong answer means.

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

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 7 of 20 problems