Cardinal Math

Two-digit subtraction with regrouping · sheet 25 of 30

Answer key

The answer, and what a wrong answer means.

The sheet
#ProblemAnswerIf they wrote…
1 83 − 46 37 43 smaller from larger47 borrows, but never pays
2 70 − 31 39 41 smaller from larger49 borrows, but never pays
3 55 − 38 17 23 smaller from larger27 borrows, but never pays
4 96 − 77 19 21 smaller from larger29 borrows, but never pays
5 70 − 32 38 42 smaller from larger48 borrows, but never pays
6 85 − 59 26 34 smaller from larger36 borrows, but never pays
7 51 − 37 14 24 borrows, but never pays26 smaller from larger
8 28 − 27 1 no pattern to catch here
9 60 − 58 2 12 borrows, but never pays18 smaller from larger
10 80 − 56 24 34 borrows, but never pays36 smaller from larger
11 74 − 38 36 44 smaller from larger46 borrows, but never pays
12 95 − 76 19 21 smaller from larger29 borrows, but never pays
13 59 − 58 1 no pattern to catch here
14 60 − 32 28 32 smaller from larger38 borrows, but never pays
15 73 − 59 14 24 borrows, but never pays26 smaller from larger
16 99 − 87 12 no pattern to catch here
17 68 − 59 9 11 smaller from larger19 borrows, but never pays
18 91 − 59 32 42 borrows, but never pays48 smaller from larger
19 79 − 39 40 no pattern to catch here
20 89 − 79 10 no pattern to catch here

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.