Answer key

The answer, and what a wrong answer means.

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