Cardinal Math

Addition with regrouping · sheet 18 of 30

Answer key

The answer, and what a wrong answer means.

The sheet
#ProblemAnswerIf they wrote…
1 47 + 56 103 913 writes the whole column sum93 forgets the ten
2 199 + 507 706 6916 writes the whole column sum696 forgets the ten796 carries two columns over
3 296 + 271 567 1467 carries two columns over4167 writes the whole column sum467 forgets the ten
4 278 + 293 571 1561 carries two columns over41611 writes the whole column sum461 forgets the ten
5 380 + 462 842 1742 carries two columns over7142 writes the whole column sum742 forgets the ten
6 420 + 183 603 1503 carries two columns over503 forgets the ten5103 writes the whole column sum
7 208 + 598 806 7916 writes the whole column sum796 forgets the ten896 carries two columns over
8 44 + 39 83 713 writes the whole column sum73 forgets the ten
9 437 + 266 703 6913 writes the whole column sum693 forgets the ten793 carries two columns over
10 47 + 26 73 613 writes the whole column sum63 forgets the ten
11 33 + 18 51 41 forgets the ten411 writes the whole column sum
12 154 + 278 432 1422 carries two columns over31212 writes the whole column sum322 forgets the ten
13 59 + 22 81 71 forgets the ten711 writes the whole column sum
14 166 + 615 781 771 forgets the ten7711 writes the whole column sum871 carries two columns over
15 109 + 229 338 3218 writes the whole column sum328 forgets the ten428 carries two columns over
16 416 + 216 632 6212 writes the whole column sum622 forgets the ten722 carries two columns over
17 41 + 59 100 90 forgets the ten910 writes the whole column sum
18 13 + 67 80 70 forgets the ten710 writes the whole column sum
19 396 + 195 591 1581 carries two columns over41811 writes the whole column sum481 forgets the ten
20 38 + 42 80 70 forgets the ten710 writes the whole column sum

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 in the guide. Problems marked "no pattern to catch" are the plain ones; a child who gets only those right is telling you something too.

Writes the whole column sum 20 of 20 problems

Writes each column's full total into the answer: 8 and 5 are 13, so 13 goes down; 3 and 4 are 7.

38 + 45 they write 713 it is 83

Forgets the ten 20 of 20 problems

Adds each column and keeps only the ones digit of the total. The ten that should move left gets dropped.

38 + 45 they write 73 it is 83

Carries two columns over 12 of 20 problems

The carried ten skips a column and lands two places left, where it's worth a hundred.

375 + 182 they write 1457 it is 557

Not sure which? The five-minute check picks the problems that tell the patterns apart and names the one it sees.