A fraction times a whole number

Difficulty Stretch · Set exn039

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1
23×10=
2
13×5=
3
1115×4=
4
23×12=
5
27×10=
6
219×8=
7
23×9=
8
516×12=
9
1113×3=
10
1116×4=
11
27×4=
12
1120×6=
13
911×6=
14
16×4=
15
310×8=
16
710×8=
17
911×2=
18
1213×11=
19
514×8=
20
37×11=

What is in this set

The numbers in this set run from 1 to 20.
Every problem in it will have a whole number on one side.
35% of them need simplifying at the end.
A careful solution takes 2 written steps on average.
The mistake this set invites most often, in 100% of the problems: the whole number multiplied the top and the bottom; multiplying by a whole number takes that many of the parts, so only the numerator grows.
Answers are a fraction in its lowest terms, written like 3/4.

Drawing 240 problems from this page produced 203 different ones, 85% — 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 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.