To divide by a fraction, flip it and multiply. Keep, change, flip.
Dividing by a fraction asks "how many of that fraction fit into this
amount?" The trick is to turn the division into a multiplication by
using the reciprocal.
The reciprocal of a fraction is that fraction flipped
upside down. The reciprocal of 32 is
23.
ba÷dc=ba×cd
The fraction bar below can help you see how many smaller pieces fit
inside the shaded region.
See it: how many fit inside?
Try:
Press Measure to watch the smaller fraction piece slide
along the shaded bar, counting how many times it fits. The count is the
same answer you get from "flip and multiply" — try each example to see
for yourself.
Watch it work
Question 1: Work out
43÷2.
Step 1: Write the whole number as a fraction. 2=12
Step 2: Flip the second fraction and multiply. 43×21=83
Answer:43÷2=83
Question 2: Work out
32÷54.
Step 1: Keep the first fraction. Flip the second. 32×45
Step 2: Multiply across. 3×42×5=1210
Step 3: Simplify. 1210=65 (divide top and bottom by 2).
Answer:32÷54=65
Have a go
Q1. Work out 21÷3.
21÷13=21×31=61
61
Q2. Work out 53÷21.
53×12=56=151
151
Q3. Work out 65÷32.
65×23=1215=45=141
141
Q4. A ribbon is 54 of a metre long.
It is cut into pieces that are each 101 of a metre.
How many pieces are there?
54÷101=54×110=540=8
8 pieces.
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