Cardinal Math

Addition with regrouping · sheet 16 of 30

Answer key

The answer, and what a wrong answer means.

The sheet
#ProblemAnswerIf they wrote…
1 18 + 18 36 216 writes the whole column sum26 forgets the ten
2 31 + 39 70 60 forgets the ten610 writes the whole column sum
3 227 + 176 403 3913 writes the whole column sum393 forgets the ten493 carries two columns over
4 397 + 252 649 1549 carries two columns over5149 writes the whole column sum549 forgets the ten
5 157 + 148 305 2915 writes the whole column sum295 forgets the ten395 carries two columns over
6 167 + 153 320 1310 carries two columns over210 forgets the ten21110 writes the whole column sum
7 389 + 512 901 891 forgets the ten8911 writes the whole column sum991 carries two columns over
8 21 + 49 70 60 forgets the ten610 writes the whole column sum
9 78 + 24 102 912 writes the whole column sum92 forgets the ten
10 588 + 378 966 1956 carries two columns over81516 writes the whole column sum856 forgets the ten
11 126 + 767 893 8813 writes the whole column sum883 forgets the ten983 carries two columns over
12 16 + 18 34 214 writes the whole column sum24 forgets the ten
13 112 + 628 740 730 forgets the ten7310 writes the whole column sum830 carries two columns over
14 18 + 44 62 512 writes the whole column sum52 forgets the ten
15 609 + 209 818 8018 writes the whole column sum808 forgets the ten908 carries two columns over
16 285 + 131 416 1316 carries two columns over3116 writes the whole column sum316 forgets the ten
17 292 + 494 786 1686 carries two columns over6186 writes the whole column sum686 forgets the ten
18 59 + 18 77 617 writes the whole column sum67 forgets the ten
19 28 + 74 102 912 writes the whole column sum92 forgets the ten
20 492 + 398 890 1880 carries two columns over71810 writes the whole column sum780 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.