A negative index as a fraction

Difficulty Stretch · Set v701ut

Write each of these as a fraction.

Fill in what you can and press Check. Nothing you type is sent anywhere.

1
7⁻¹=
2
7⁻³=
3
9⁻²=
4
5⁻³=
5
7⁻⁴=
6
6⁻¹=
7
2⁻¹=
8
5⁻¹=
9
3⁻¹=
10
3⁻²=
11
3⁻⁴=
12
3⁻²=
13
3⁻¹=
14
7⁻²=
15
8⁻⁴=
16
3⁻²=
17
11⁻³=
18
10⁻⁴=
19
7⁻³=
20
4⁻⁴=

What is in this set

The numbers in this set run from 1 to 12.
Every problem in it will carry a negative index.
A careful solution takes 2 written steps on average.
The mistake this set invites most often, in 100% of the problems: the minus was put in front of the answer; a negative index turns the power upside down instead.
Answers are a fraction in its lowest terms, written like 3/4.

Drawing 240 problems from this page produced 44 different ones, 18% — 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 8 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.