The missing numerator in an equivalent fraction

Difficulty Standard · Set r605l6

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1
17=?42— what is the numerator?
2
311=?44— what is the numerator?
3
512=?60— what is the numerator?
4
12=?8— what is the numerator?
5
14=?24— what is the numerator?
6
25=?20— what is the numerator?
7
911=?66— what is the numerator?
8
47=?28— what is the numerator?
9
16=?12— what is the numerator?
10
34=?24— what is the numerator?
11
47=?21— what is the numerator?
12
17=?28— what is the numerator?
13
47=?28— what is the numerator?
14
911=?55— what is the numerator?
15
59=?27— what is the numerator?
16
12=?4— what is the numerator?
17
35=?15— what is the numerator?
18
25=?30— what is the numerator?
19
58=?32— what is the numerator?
20
34=?24— what is the numerator?

What is in this set

The numbers in this set run from 1 to 72.
A careful solution takes 2 written steps on average.
The mistake this set invites most often, in 100% of the problems: the denominator grew by 27 and the same amount was added on top.
Answers are a whole number.

Drawing 240 problems from this page produced 137 different ones, 57% — so a sheet of 20 will come back to a problem you have seen — there are only so many sensible ones of this kind.

The same skill, harder or easier

We would put this in front of a grade 4 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.