Cardinal Math

Three-digit subtraction with regrouping · sheet 23 of 30

Answer key

The answer, and what a wrong answer means.

The sheet
#ProblemAnswerIf they wrote…
1 368 − 193 175 235 smaller from larger275 borrows, but never pays
2 307 − 188 119 219 borrowing through a zero229 borrows, but never pays281 smaller from larger
3 401 − 210 191 201 zero minus a number is zero211 smaller from larger or zero minus a number is the number291 borrows, but never pays
4 269 − 116 153 no pattern to catch here
5 212 − 170 42 142 borrows, but never pays162 smaller from larger
6 706 − 317 389 411 smaller from larger489 borrowing through a zero499 borrows, but never pays
7 487 − 289 198 202 smaller from larger208 borrows, but never pays
8 406 − 193 213 303 zero minus a number is zero313 borrows, but never pays393 smaller from larger or zero minus a number is the number
9 612 − 422 190 210 smaller from larger290 borrows, but never pays
10 205 − 145 60 100 zero minus a number is zero140 smaller from larger or zero minus a number is the number160 borrows, but never pays
11 240 − 152 88 112 smaller from larger198 borrows, but never pays90 zero minus a number is zero92 zero minus a number is the number
12 602 − 115 487 513 smaller from larger587 borrowing through a zero597 borrows, but never pays
13 666 − 199 467 533 smaller from larger577 borrows, but never pays
14 208 − 109 99 101 smaller from larger109 borrows, but never pays199 borrowing through a zero
15 830 − 287 543 550 zero minus a number is zero557 zero minus a number is the number653 borrows, but never pays657 smaller from larger
16 870 − 466 404 410 zero minus a number is zero414 borrows, but never pays416 smaller from larger or zero minus a number is the number
17 933 − 723 210 no pattern to catch here
18 577 − 469 108 112 smaller from larger118 borrows, but never pays
19 876 − 147 729 731 smaller from larger739 borrows, but never pays
20 261 − 187 74 126 smaller from larger184 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 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 6 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 6 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.