Answer key

The answer, and what a wrong answer means.

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