NARRATOR: Hello you two.
Where are you going?
SNOOT: (ALIEN LANGUAGE)
NARRATOR: Ah, I see…
Time to refuel your flying saucer at the space station.
(ALARM SOUNDING)
NARRATOR: What’s that alarm for?
SNOOT: (ALIEN LANGUAGE)
NARRATOR: Unidentified ships in your sector!
How many are there?
There are 19 squadrons with 5 ships in each squadron.
It looks like an attack force!
Better call the space station and let them know.
But how many ships are there altogether?
SNOOT: Er… Uh…
NARRATOR: Why not split up the 19 squadrons into 1 group of 10 and another group of 9?
There are 5 ships in each squadron.
10 times 5 is 50 and 9 times 5 is 45.
50 add 45 is 95 ships altogether.
FIN: (ALIEN LANGUAGE)
NARRATOR: OK Fin, if you’ve got a better way of working it out…
19 is only 1 away from 20, so you prefer to start by multiplying 20 times 5, which equals 100.
Then we need to take away a squadron of 5, because there are actually only 19 squadrons, not 20.
100 take away 5 is 95 ships altogether.
BOTH: Aha!
NARRATOR: Oh no! The attack force is here.
(TINY ALARM)
NARRATOR: Oh…
They looked a lot bigger on the computer.
Description
When multiplying a 2-digit number by a 1-digit number you can use both mental and written methods. Let’s take a look at an example of solving a multiplication problem in your head.
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