Cardinal Math

Two-digit subtraction with regrouping · sheet 26 of 30

Answer key

The answer, and what a wrong answer means.

The sheet
#ProblemAnswerIf they wrote…
1 85 − 28 57 63 smaller from larger67 borrows, but never pays
2 88 − 87 1 no pattern to catch here
3 80 − 59 21 31 borrows, but never pays39 smaller from larger
4 21 − 17 4 14 borrows, but never pays16 smaller from larger
5 60 − 41 19 21 smaller from larger29 borrows, but never pays
6 90 − 84 6 14 smaller from larger16 borrows, but never pays
7 86 − 57 29 31 smaller from larger39 borrows, but never pays
8 90 − 86 4 14 borrows, but never pays16 smaller from larger
9 91 − 58 33 43 borrows, but never pays47 smaller from larger
10 95 − 38 57 63 smaller from larger67 borrows, but never pays
11 90 − 88 2 12 borrows, but never pays18 smaller from larger
12 93 − 26 67 73 smaller from larger77 borrows, but never pays
13 83 − 67 16 24 smaller from larger26 borrows, but never pays
14 46 − 16 30 no pattern to catch here
15 18 − 16 2 no pattern to catch here
16 64 − 57 7 13 smaller from larger17 borrows, but never pays
17 96 − 62 34 no pattern to catch here
18 96 − 80 16 no pattern to catch here
19 94 − 75 19 21 smaller from larger29 borrows, but never pays
20 96 − 89 7 13 smaller from larger17 borrows, but never pays

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.

Borrows, but never pays 15 of 20 problems

Adds ten to the ones but leaves the tens alone. Looks like borrowing; the answer is ten too big.

52 − 38 they write 24 it is 14

Smaller from larger 15 of 20 problems

Takes the smaller digit from the bigger one in every column, whichever is on top. Never borrows.

52 − 38 they write 26 it is 14

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