Cardinal Math

Addition with regrouping · sheet 21 of 30

Answer key

The answer, and what a wrong answer means.

The sheet
#ProblemAnswerIf they wrote…
1 116 + 136 252 2412 writes the whole column sum242 forgets the ten342 carries two columns over
2 17 + 15 32 212 writes the whole column sum22 forgets the ten
3 76 + 29 105 915 writes the whole column sum95 forgets the ten
4 121 + 719 840 830 forgets the ten8310 writes the whole column sum930 carries two columns over
5 497 + 186 683 1673 carries two columns over51713 writes the whole column sum573 forgets the ten
6 44 + 29 73 613 writes the whole column sum63 forgets the ten
7 73 + 27 100 90 forgets the ten910 writes the whole column sum
8 347 + 258 605 5915 writes the whole column sum595 forgets the ten695 carries two columns over
9 283 + 358 641 1631 carries two columns over51311 writes the whole column sum531 forgets the ten
10 281 + 171 452 1352 carries two columns over3152 writes the whole column sum352 forgets the ten
11 193 + 396 589 1489 carries two columns over4189 writes the whole column sum489 forgets the ten
12 174 + 781 955 1855 carries two columns over8155 writes the whole column sum855 forgets the ten
13 389 + 219 608 5918 writes the whole column sum598 forgets the ten698 carries two columns over
14 273 + 129 402 3912 writes the whole column sum392 forgets the ten492 carries two columns over
15 38 + 34 72 612 writes the whole column sum62 forgets the ten
16 22 + 48 70 60 forgets the ten610 writes the whole column sum
17 277 + 463 740 1730 carries two columns over61310 writes the whole column sum630 forgets the ten
18 65 + 25 90 80 forgets the ten810 writes the whole column sum
19 249 + 312 561 551 forgets the ten5511 writes the whole column sum651 carries two columns over
20 46 + 47 93 813 writes the whole column sum83 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.