A number as a product of primes

Difficulty Starter · Set 07ldpw

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1
Write 44 as a product of prime numbers, smallest first, separated by ×.
2
Write 52 as a product of prime numbers, smallest first, separated by ×.
3
Write 48 as a product of prime numbers, smallest first, separated by ×.
4
Write 48 as a product of prime numbers, smallest first, separated by ×.
5
Write 27 as a product of prime numbers, smallest first, separated by ×.
6
Write 55 as a product of prime numbers, smallest first, separated by ×.
7
Write 20 as a product of prime numbers, smallest first, separated by ×.
8
Write 51 as a product of prime numbers, smallest first, separated by ×.
9
Write 52 as a product of prime numbers, smallest first, separated by ×.
10
Write 46 as a product of prime numbers, smallest first, separated by ×.
11
Write 57 as a product of prime numbers, smallest first, separated by ×.
12
Write 49 as a product of prime numbers, smallest first, separated by ×.
13
Write 44 as a product of prime numbers, smallest first, separated by ×.
14
Write 46 as a product of prime numbers, smallest first, separated by ×.
15
Write 39 as a product of prime numbers, smallest first, separated by ×.
16
Write 55 as a product of prime numbers, smallest first, separated by ×.
17
Write 57 as a product of prime numbers, smallest first, separated by ×.
18
Write 20 as a product of prime numbers, smallest first, separated by ×.
19
Write 42 as a product of prime numbers, smallest first, separated by ×.
20
Write 38 as a product of prime numbers, smallest first, separated by ×.

What is in this set

The numbers in this set run from 12 to 60.
89% of them use more than one prime.
11% of them are a power of a single prime.
A careful solution takes 2.9 written steps on average.
The mistake this set invites most often, in 55% of the problems: a prime that divides more than once has to appear more than once in the product.
Answers are a short answer exactly as the problem asks for it.

Drawing 240 problems from this page produced 36 different ones, 15% — 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 6 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.