Missing number in a 2-digit subtraction

Difficulty Standard · Set ic7lwo

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1
94−=15
2
106−=35
3
51−=18
4
148−=63
5
90−=11
6
135−=66
7
108−=51
8
72−=59
9
102−=27
10
138−=92
11
117−=84
12
117−=29
13
136−=75
14
31−=19
15
136−=37
16
167−=82
17
128−=78
18
130−=87
19
53−=38
20
101−=32

What is in this set

The numbers in this set run from 10 to 188.
Every problem in it will need a borrow from the column to the left.
A careful solution takes 2 written steps on average.
The mistake this set invites most often, in 100% of the problems: the two numbers on the page were added — a missing part is found by taking one away from the total, not by adding.
Answers are a whole number.

Drawing 240 problems from this page produced 234 different ones, 98% — so a sheet of 20 is a new sheet almost every time.

The same skill, harder or easier

We would put this in front of a grade 3 class. That is our judgement, not a standard, and it is printed here so you can disagree with it. Everything else we put in that year.