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Example 2

 

 

Sally's mother asked her to go to the market to buy some things. She gave her \(\text{Rs. }1265\)

Sally bought 1 kg of ghee for \(\text{Rs. }146\), one pack of detergent for \(\text{Rs. }320\), 1 litre of milk for \(\text{Rs. }120\) and one pack of butter for \(\text{Rs. }95\)

The shopkeeper gave her back \(\text{Rs. }584\)

Did the shopkeeper give her the right amount?

Solution:

Let's find the total amount of money spent by Sally.

Money spent on ghee = \(\text{Rs. }146\)

Money spent on detergent = \(\text{Rs. }320\)

Money spent on milk = \(\text{Rs. }120\)

Money spent on butter = \(\text{Rs. }95\)

Total money spent by Sally:

\(\begin{align} &=\! \text{Rs. }146 \!+\! \text{Rs. }320 \!+\! \text{Rs. }120 \!+\! \text{Rs. }95\\ &=\! \text{Rs. }681\end{align}\)

Now, let's subtract 681 from 1265 to find the money given by the shopkeeper to Sally.

The problem can be written as:

Remember that we borrow when we don't have enough.

Take away 1 from 5 ones.

We are now left with 4 ones.

We cannot take away 8 tens from 6 tens.

Hence, we borrow 1 hundreds which is equal to 10 tens.

Now we have 16 tens out of which we take away 8 tens.

We are left with 8 tens.

Finally, we are left with 1 hundreds.

Similarly, we cannot take 6 hundreds from 1 hundreds.

Hence, we borrow 1 thousands which is equal to 10 hundreds.

Taking away 6 hundreds from 11 hundreds gives us 5 hundreds.

The shopkeeper must return \(\text{Rs. } 584\) to Sally.

\(\therefore\) The shopkeeper gave Sally the right amount.

Finding a difference between two large numbers can be a challenge.

Use this strategy called removal to make it slighty easier to subtract two numbers.