Cardinal Math

Addition with regrouping · sheet 28 of 30

Answer key

The answer, and what a wrong answer means.

The sheet
#ProblemAnswerIf they wrote…
1 36 + 14 50 40 forgets the ten410 writes the whole column sum
2 15 + 15 30 20 forgets the ten210 writes the whole column sum
3 27 + 73 100 90 forgets the ten910 writes the whole column sum
4 327 + 305 632 6212 writes the whole column sum622 forgets the ten722 carries two columns over
5 45 + 39 84 714 writes the whole column sum74 forgets the ten
6 497 + 487 984 1974 carries two columns over81714 writes the whole column sum874 forgets the ten
7 63 + 17 80 70 forgets the ten710 writes the whole column sum
8 54 + 16 70 60 forgets the ten610 writes the whole column sum
9 144 + 176 320 1310 carries two columns over210 forgets the ten21110 writes the whole column sum
10 259 + 143 402 3912 writes the whole column sum392 forgets the ten492 carries two columns over
11 15 + 85 100 90 forgets the ten910 writes the whole column sum
12 244 + 258 502 4912 writes the whole column sum492 forgets the ten592 carries two columns over
13 28 + 18 46 316 writes the whole column sum36 forgets the ten
14 427 + 277 704 6914 writes the whole column sum694 forgets the ten794 carries two columns over
15 262 + 218 480 470 forgets the ten4710 writes the whole column sum570 carries two columns over
16 109 + 124 233 2213 writes the whole column sum223 forgets the ten323 carries two columns over
17 161 + 297 458 1358 carries two columns over3158 writes the whole column sum358 forgets the ten
18 198 + 289 487 1477 carries two columns over31717 writes the whole column sum377 forgets the ten
19 585 + 172 757 1657 carries two columns over6157 writes the whole column sum657 forgets the ten
20 183 + 183 366 1266 carries two columns over2166 writes the whole column sum266 forgets the ten

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.