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Column subtraction: Lesson 1: dolphins

3 - Whiteboard Challenges

Spot the Mistake!

Someone has made a mistake in their column subtraction. Can you explain the mistake to your talk partner?

Did you know?

A spinner dolphin can find food and avoid predators in the dark depths of the ocean by making high-pitched clicking sounds. (The sounds bounce off an object and return to the dolphin, giving it information about the object’s size and location.)

Use PAWS, counters and column subtraction to solve the following word problem.

It was night-time and a large pod of 267 spinner dolphins were feeding. One spinner dolphin dived 164 metres below the surface of the water to catch a squid. After eating the squid, it rose 73 metres to catch a fish.

How many metres below the surface of the water was the spinner dolphin when it caught the fish?