Mon 21st Nov – Multiplying by 20, 200, 200 and 30, 300 3000

LEARNING OBJECTIVE: To utilise the skills gained in multiplying by 10,100, 1000 to help multiply by other numbers

SUCCESS CRITERIA: You will be able to multiply 2 and 3 digit numbers by 20,200, 2000, 30, 300 and 3000 without a calculator

STARTER: Without a calculator write down the answers to these 12 sums:

2 x 13 = 3 x 15 = 2 x 23 = 3 x 25 = 2 x 45 = 3 x 33 =

2 x 123 = 3 x 110 = 2 x 245 = 3 x 140 = 2 x 336 = 3 x 145 =

 

LESSON: Ensure all students can do the above sums by checking answers and getting feedback

Quick reminder of using grid to multiply by 10, 100, 1000

Show

20 = 2 x 10    30 = 3 x 10

200 = 2 x 100    300 = 3 x 100

2000 = 2 x 1000    3000 = 3 x 1000

Example 20 x 45

Step 1 multiply 45 by 10 to give 450

Step 2 multiply answer (450) by 2 which gives and answer of 900

Try other examples using 20, 30, 200, 300 on IWB

Use the same method to solve these sums WITHOUT a Calculator

SHOW BOTH STAGES OF YOUR WORKING OUT FOR EACH QUESTION

20 x 13 = 30 x 15 = 200 x 23 = 300 x 25 = 20 x 45 = 30 x 33 = 200 x 123 = 300 x 110 = 200 x 245 = 300 x 140 =

20 x 336 = 30 x 145 = 2000 x 35 = 3000 x 23 = 2000 x 95 = 3000 x 82 = 2000 x 354 = 400 x 35 = 600 x 12 = 800 x 121 =

 

PLENARY: Checking answers, feedback from students on success