Grade 2 · 2.NBT.5 · sheet 12 of 30
Two-digit subtraction with regrouping
A printable worksheet, new every day, with a key that names the mistake.
- Twenty problems: fifteen need a ten opened, five do not, mixed. A new sheet every day, and every sheet has its own key.
- The key does more than mark. For each problem it lists the wrong answers the common mistakes produce, so "they wrote 26" tells you which rule your child is following.
Two-digit subtraction with regrouping
Show your work. If the top digit is smaller, open a ten.
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1
99 −86
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2
80 −69
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3
67 −28
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4
59 −29
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5
80 −28
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6
88 −79
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7
60 −29
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8
82 −80
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9
93 −27
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10
77 −29
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11
92 −89
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12
90 −83
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13
39 −37
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14
40 −22
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15
86 −69
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16
96 −19
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17
83 −37
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18
72 −62
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19
92 −85
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20
31 −19
The app does this live.
It picks the next problem from the last answer, skips ahead or doubles back, and animates the ten bursting into ones instead of telling your child to cross something out. The five-minute check on the guide is the same engine in your browser, and the guide explains each of the patterns the key names.
How to use the key
Mark the sheet against the key. Beside each answer it lists what the known mistakes would have written. One wrong answer is a slip. The same pattern three times is a rule your child is following, and the guide says what to do about it tonight.
On this sheet the key can tell apart: borrows, but never pays (15 problems), smaller from larger (15 problems).
Cardinal Math watches for all of these, every day.
Inside the app the same patterns are caught as your child plays, across the whole of K to grade 5, and explained to you in plain words. One price, no ads, no streaks. Coming to iPhone and iPad.
Tell me when it's out