Answer key

The answer, and what a wrong answer means.

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