Raj uses these methods to work out and check his answer.

Question: Work out $0.45\times 372$.

Solution: First work out $45\times 372$.

$\times$	$300$	$70$	$2$
$40$	$12000$	$2800$	$80$
$5$	$1500$	$350$	$10$
Total	$13500$	$3150$	$90$

$\begin{array}{ccccc}1& 3& 5& 0& 0\\ & 3& 1& 5& 0\\ +& & & 9& 0\\ 1& 6& 7& 4& 0\end{array}$

So, $0.45\times 372=167.40=167.4$

Check: Round $0.45 \text{to} 0.5$.

Round $372 \text{to} 400$.

$0.5\times 400=200$, which is close to $167.4$.

Can you improve his method?.

Work out this multiplication. Show how to check your answer.

$3.2\times 52$

Work out this multiplication. Show how to check your answer.

$8.1\times 384$

Work out this multiplication. Show how to check your answer.

$0.78\times 41$

This is part of Anna's homework.

Questions: work out $47.35\times 18$.

Solution: First work out $4735\times 18$.

So, $47.35\times 18=85.23$

Without checking the method and working out the answer, how can you tell that Anna is incorrect?

Work out $47.35\times 18$. Work out the correct answer, showing all your working. 

 Samir manages a hotel. The table shows the cost of items that he buys for the hotel bathrooms. 

Samir buys: 

• $350$ bottles of shampoo 
• $425$ bottles of shower gel 
• $275$ bottles or hand lotion 
• $600$ bars of soap.