Cardinal Math

Three-digit subtraction with regrouping · sheet 4 of 30

Answer key

The answer, and what a wrong answer means.

The sheet
#ProblemAnswerIf they wrote…
1 200 − 138 62 100 zero minus a number is zero138 smaller from larger or zero minus a number is the number162 borrowing through a zero172 borrows, but never pays
2 434 − 144 290 310 smaller from larger390 borrows, but never pays
3 761 − 599 162 238 smaller from larger272 borrows, but never pays
4 180 − 127 53 60 zero minus a number is zero63 borrows, but never pays67 smaller from larger or zero minus a number is the number
5 809 − 717 92 102 zero minus a number is zero112 smaller from larger or zero minus a number is the number192 borrows, but never pays
6 687 − 467 220 no pattern to catch here
7 503 − 169 334 434 borrowing through a zero444 borrows, but never pays466 smaller from larger
8 757 − 264 493 513 smaller from larger593 borrows, but never pays
9 841 − 576 265 335 smaller from larger375 borrows, but never pays
10 706 − 587 119 219 borrowing through a zero229 borrows, but never pays281 smaller from larger
11 865 − 806 59 61 smaller from larger69 borrows, but never pays
12 664 − 226 438 442 smaller from larger448 borrows, but never pays
13 208 − 149 59 141 smaller from larger159 borrowing through a zero169 borrows, but never pays
14 460 − 193 267 270 zero minus a number is zero273 zero minus a number is the number333 smaller from larger377 borrows, but never pays
15 976 − 389 587 613 smaller from larger697 borrows, but never pays
16 868 − 511 357 no pattern to catch here
17 805 − 465 340 400 zero minus a number is zero440 borrows, but never pays460 smaller from larger or zero minus a number is the number
18 901 − 721 180 200 zero minus a number is zero220 smaller from larger or zero minus a number is the number280 borrows, but never pays
19 733 − 340 393 413 smaller from larger493 borrows, but never pays
20 220 − 182 38 148 borrows, but never pays162 smaller from larger40 zero minus a number is zero42 zero minus a number is the number

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 18 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 18 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

Zero minus a number is the number 7 of 20 problems

When the top digit is 0, writes the bottom digit as that column's answer.

40 − 27 they write 27 it is 13

Zero minus a number is zero 7 of 20 problems

When the top digit is 0, writes 0 for that column.

40 − 27 they write 20 it is 13

Borrowing through a zero 4 of 20 problems

Turns the 0 into a 9 and gives the ones their ten, but never reduces the column left of the zero.

302 − 167 they write 235 it is 135

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