# Column subtraction: Lesson 1: dolphins

## The Lesson

*Click on the tabs below or click here to view in PowerPoint.*

In this exciting lesson, you will need to solve a range of subtraction word problems that feature dolphins. Try using **PAWS** to arrive at the right answer!

**P ** = Picture the problem in your mind.

**A **= Annotate the word problem by highlighting the important information.

**W** = Write down the number sentence that needs to be solved.

**S** = Solve the number sentence using an efficient strategy.

**Useful prior knowledge:**

- To confidently subtract a 2-digit number from a 2-digit number (with one exchange).

**Did you know?**

Scientists think that another reason that a spinner dolphin spins is to shake off parasites that have attached themselves to its skin.

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

A twenty-year old spinner dolphin had 176 tiny parasites on its body. After making 56 spinning leaps in the Pacific Ocean, it managed to remove a total of 57 parasites from its body.

**How many parasites did the spinner dolphin have on its body after leaping this many times?**