Cardinal Math

Two-digit subtraction with regrouping · sheet 17 of 30

Answer key

The answer, and what a wrong answer means.

The sheet
#ProblemAnswerIf they wrote…
1 73 − 64 9 11 smaller from larger19 borrows, but never pays
2 26 − 25 1 no pattern to catch here
3 59 − 58 1 no pattern to catch here
4 57 − 47 10 no pattern to catch here
5 68 − 49 19 21 smaller from larger29 borrows, but never pays
6 94 − 75 19 21 smaller from larger29 borrows, but never pays
7 76 − 39 37 43 smaller from larger47 borrows, but never pays
8 83 − 77 6 14 smaller from larger16 borrows, but never pays
9 69 − 58 11 no pattern to catch here
10 90 − 66 24 34 borrows, but never pays36 smaller from larger
11 95 − 84 11 no pattern to catch here
12 95 − 48 47 53 smaller from larger57 borrows, but never pays
13 96 − 87 9 11 smaller from larger19 borrows, but never pays
14 90 − 76 14 24 borrows, but never pays26 smaller from larger
15 95 − 18 77 83 smaller from larger87 borrows, but never pays
16 62 − 14 48 52 smaller from larger58 borrows, but never pays
17 60 − 59 1 11 borrows, but never pays19 smaller from larger
18 60 − 54 6 14 smaller from larger16 borrows, but never pays
19 64 − 57 7 13 smaller from larger17 borrows, but never pays
20 90 − 11 79 81 smaller from larger89 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.