Cardinal Math

Three-digit subtraction with regrouping · sheet 22 of 30

Answer key

The answer, and what a wrong answer means.

The sheet
#ProblemAnswerIf they wrote…
1 209 − 197 12 102 zero minus a number is zero112 borrows, but never pays192 smaller from larger or zero minus a number is the number
2 303 − 165 138 238 borrowing through a zero248 borrows, but never pays262 smaller from larger
3 804 − 474 330 400 zero minus a number is zero430 borrows, but never pays470 smaller from larger or zero minus a number is the number
4 782 − 287 495 505 borrows, but never pays or smaller from larger
5 901 − 456 445 545 borrowing through a zero555 borrows, but never pays or smaller from larger
6 907 − 131 776 806 zero minus a number is zero836 smaller from larger or zero minus a number is the number876 borrows, but never pays
7 562 − 190 372 432 smaller from larger472 borrows, but never pays
8 440 − 185 255 260 zero minus a number is zero265 zero minus a number is the number345 smaller from larger365 borrows, but never pays
9 187 − 148 39 41 smaller from larger49 borrows, but never pays
10 400 − 357 43 100 zero minus a number is zero143 borrowing through a zero153 borrows, but never pays157 smaller from larger or zero minus a number is the number
11 560 − 165 395 400 zero minus a number is zero405 borrows, but never pays or smaller from larger or zero minus a number is the number
12 504 − 446 58 142 smaller from larger158 borrowing through a zero168 borrows, but never pays
13 228 − 109 119 121 smaller from larger129 borrows, but never pays
14 842 − 640 202 no pattern to catch here
15 983 − 685 298 302 smaller from larger308 borrows, but never pays
16 947 − 337 610 no pattern to catch here
17 235 − 192 43 143 borrows, but never pays163 smaller from larger
18 573 − 416 157 163 smaller from larger167 borrows, but never pays
19 420 − 145 275 280 zero minus a number is zero285 zero minus a number is the number325 smaller from larger385 borrows, but never pays
20 266 − 174 92 112 smaller from larger192 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 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.