Step by step
The question
Question: change 3 days into hours.
3 day = ? h
1 Find the link
1 day is 24 hours.
1 day = 24 h
2 Make the unit fraction
We want hours, so hours go on top.
We have days, so days go at the bottom.
Top and bottom are the same amount.
So the fraction is 1, and times 1 keeps the size.
24 h1 day = 1
Careful!
Not upside down.
Then the days would not cross out.
Careful: not 3 day × 1 day24 h ✗
3 Multiply
We multiply 3 days by the fraction.
3 day = 3 day × 24 h1 day
Days on top and at the bottom cancel, like numbers.
Cross them out.
Hours are left.
What is left: 3 times 24.
= 3 × 24 h
3 times 24 is 72.
So 3 days is 72 hours.
= 72 h
4 Check
Does it make sense?
Hours are smaller than days.
So we need more of them.
72 is more than 3.
Yes.
h smaller than day → more: 72 > 3
And back the other way: 72 divided by 24 = 3.
We get 3 days again.
So the answer is right!
back: 72 ÷ 24 = 3
Let's look back.
First: find the link.
Then: make the unit fraction.
Then: multiply.
Last: check.
Answer
= 72 h