Mathematics

Yesterday we did some Mathematics and these are some of the   Marilyn needs to fertilise her front lawn. It measures 20 metres by 35 metres. Each bag of the fertiliser that she plans to use covers approximately 200m2. How many bags should she buy?

She needs to buy 3 and a 1/2 bags .20x35=700 and 700 divided by 200 = 3.5 and she has a 700 metre squared lawn and 3 bags would cover 600 metres squared and half the bag would cover the left over 100 metre squared.

Remember: length X width

2) Mr Masua needs to fertilise our school lawn. It measures 35 metres by 40 metres. Each bag of the fertiliser that he plans to use covers approximately 200m2. How many bags should he buy?

30x40=1200

5 x 40=200

35 x 40 = 200

30 x 20 x 2 + 200 = 1400

she needs to buy 7 bags

Decimals maintenance (Write down the strategies you use)

Sally was painting her house. She needed 0.48 litres for each wall of her kitchen and 1.34 litres for each wall of her bedroom.

How many litres does she need for the kitchen?

0.40 x 4 = 1.6

0.8 x 4 = 0.36

1.6 + 0.32 = 1.92

How many litres does she need for the bedroom?

1 x 4 = 4.0

0.30 x 4 = 1.20

0.4 x 4 = 0.16

4.0 + 1.0 = 5.0

0.20 + 0.16 = 0.36

5.0 + 0.36 = 5.36

1.0 x 4 = 4

3.98 + 12.34 = 16.32

0.089 + 0.834 = 0.932

Which is bigger? 0.89 or 0.782

0.98 - 0.234 = 0.746

0.5 - 0.24 = 0.26

12.89 - 9.242 = 3.648

Have a look at these strategies and try them out to solve the problem.

Place value partitioning: 35 x 20 = (30 +5) x 20 = (30 x 20) + (5 x20) = 600 + 100 = 700

Rounding and compensating: 20X35 (20 X 40 - 100 = 700)

Using known facts: 5, 10, 20

20X35 (20X10 + 20X10 + 20X10 + 20 X 5 =700)

Vertical algorithm: Traditional algorithm

 20

X35

Reversibility: 20X35 (700 divided by 35 = 20 or 700 divided by 20 = 35)

Proportional adjustment: 20 X 35 =  (10X70=700)

Multiplying larger numbers

20 X 35 = (20X30 + 20X5=)