Answer key

The answer, and what a wrong answer means.

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