Created by Mr. Lafferty Maths Dept. Whole Numbers National 4 NUM 1.2 Rounding to nearest 10,100,1000 Estimating Answers Multiplying & Dividing by 10,100,1000 www.mathsrevision.com Multiplying & Dividing by 20, 300 etc.. 19-Apr-17 Created by Mr. Lafferty Maths Dept.

Created by Mr. Lafferty Maths Dept. Starter Questions National 4 NUM 1.2 www.mathsrevision.com 28o 19-Apr-17 Created by Mr. Lafferty Maths Dept.

Created by Mr. Lafferty Maths Dept. Whole Numbers National 4 NUM 1.2 Rounding to nearest 10, 100 and 1000 Learning Intention Success Criteria 1. Understand the rules for rounding to the nearest 10, 100, 1000. 1. To round numbers to the nearest 10, 100 and 1000. 2. Apply rules to problems. www.mathsrevision.com 19-Apr-17 Created by Mr. Lafferty Maths Dept.

Created by Mr. Lafferty Maths Dept. Whole Numbers National 4 NUM 1.2 Rounding to nearest 10, 100 and 1000 To round to the nearest 10 : look at the units digit: - If it is a 0, 1, 2, 3, 4 leave the 10’s digit as it is. - If it is a 5, 6, 7, 8, 9 round the 10’s digit up by 1. www.mathsrevision.com To round to the nearest 100 : look at the tens digit: - If it is a 0, 1, 2, 3, 4 leave the 100’s digit as it is. - If it is a 5, 6, 7, 8, 9 round the 100’s digit up by 1. 19-Apr-17 Created by Mr. Lafferty Maths Dept.

Created by Mr. Lafferty Maths Dept. Whole Numbers National 4 NUM 1.2 Rounding to nearest 10, 100 and 1000 To round to the nearest 1000 : look at the hundreds digit: - If it is a 0, 1, 2, 3, 4 leave the 1000’s digit as it is. - If it is a 5, 6, 7, 8, 9 round the 1000’s digit up by 1. www.mathsrevision.com Example : Round 3467 to the nearest 10, 100, 1000 The nearest 10 : 3467 3470 - look at the units digit : The nearest 100 : 3467 3500 - look at the tens digit : The nearest 1000 :3467 3000 - look at the hundreds digit: 19-Apr-17 Created by Mr. Lafferty Maths Dept.

Created by Mr. Lafferty Maths Dept. Whole Numbers National 4 NUM 1.2 Rounding to nearest 10, 100 and 1000 Example : Round 18 565 to the nearest 10, 100, 1000 The nearest 10 : 18 565 - look at the units digit : 18 570 The nearest 100 : 18 565 - look at the tens digit : 18 600 The nearest 1000 :18565 - look at the hundreds digit: 19 000 www.mathsrevision.com 19-Apr-17 Created by Mr. Lafferty Maths Dept.

Created by Mr. Lafferty Maths Dept. Whole Numbers National 4 NUM 1.2 Rounding to nearest 10, 100 and 1000 Now try Ex 1 & 2 Last 2 columns Ch1 (page 9) www.mathsrevision.com 19-Apr-17 Created by Mr. Lafferty Maths Dept.

Created by Mr. Lafferty Maths Dept. Starter Questions National 4 NUM 1.2 www.mathsrevision.com 42o 19-Apr-17 Created by Mr. Lafferty Maths Dept.

Created by Mr. Lafferty Maths Dept. Whole Numbers National 4 NUM 1.2 Using Rounding to Estimate Answers Learning Intention Success Criteria 1. Be able to round numbers to a whole number. 1. To explain how estimate answer by rounding a number to an easier number for mental calculation 2. Estimate the answer to a difficult calculation using easier whole numbers. www.mathsrevision.com 19-Apr-17 Created by Mr. Lafferty Maths Dept.

Whole Numbers www.mathsrevision.com 40 x 50 = 400 x 5 = 2000 National 4 NUM 1.2 Using Rounding to Estimate Answers It is very important when solving problems that we have a rough idea of the answer we are expecting. Example : Mentally estimate the answer to 42 x 49 Easiest way, is to round the two numbers first www.mathsrevision.com 40 x 50 = 400 x 5 = 2000 19-Apr-17 Created by Mr. Lafferty Maths Dept.

Created by Mr. Lafferty Maths Dept. Whole Numbers National 4 NUM 1.2 Using Rounding to Estimate Answers Example : Mentally estimate the answer to 104 x 19 Easiest way, is to round the two numbers first 100 x 20 = 1000 x 2 = 2000 www.mathsrevision.com Example : Mentally estimate the answer to 878 ÷ 27 Easiest way, is to round the two numbers first 900 ÷ 30 = 90 ÷ 3 = 30 19-Apr-17 Created by Mr. Lafferty Maths Dept.

Created by Mr. Lafferty Maths Dept. Whole Numbers National 4 NUM 1.2 Using Rounding to Estimate Answers Now try Ex 3 Ch1 (page 10) www.mathsrevision.com 19-Apr-17 Created by Mr. Lafferty Maths Dept.

Created by Mr. Lafferty Maths Dept. Starter Questions National 4 NUM 1.2 www.mathsrevision.com 34o 19-Apr-17 Created by Mr. Lafferty Maths Dept.

Created by Mr. Lafferty Maths Dept. Whole Numbers National 4 NUM 1.2 Multiply by 10, 100, 1000 Learning Intention Success Criteria 1. To understand how to multiply and divide simple whole numbers by 10, 100, 1000. Understand the simple rules to multiply and divide simple whole numbers. 2. Be able do simple calculations. www.mathsrevision.com 19-Apr-17 Created by Mr. Lafferty Maths Dept.

Whole Numbers www.mathsrevision.com Multiply by 10, 100, 1000 National 4 NUM 1.2 Multiply by 10, 100, 1000 For this section you need to know your tables To multiply by 10, 100, 1000 To multiply by 10 simply add a zero to the number To multiply by 100 simply add 2 zero’s to the number www.mathsrevision.com To multiply by 1000 simply add 3 zero’s to the number Example : Multiply 36 by 10, 100, 1000. Guess rule for 1000 36 x 10 = 360 36 x 100 = 3600 36 x 1000 = 36000 19-Apr-17 Created by Mr. Lafferty Maths Dept.

Whole Numbers www.mathsrevision.com Multiply by 10, 100, 1000 National 4 NUM 1.2 Multiply by 10, 100, 1000 Example : A box of crisps contain 48 packets. How many in 100 boxes ? 48 x 100 = 4800 www.mathsrevision.com 19-Apr-17 Created by Mr. Lafferty Maths Dept.

Whole Numbers www.mathsrevision.com Divide by 10, 100, 1000 National 4 NUM 1.2 Divide by 10, 100, 1000 Try and write down rule for 100, 1000 To Divide by 10, 100, 1000 To divide by 10 remove a zero from the number To divide by 100 remove 2 zero’s from the number To divide by 1000 remove 3 zero’s from the number www.mathsrevision.com Example : Divide 54000 by 10, 100, 1000. 54000÷ 10 = 5400 54000 ÷ 100 = 540 54000 ÷ 1000 = 54 19-Apr-17 Created by Mr. Lafferty Maths Dept.

Created by Mr. Lafferty Maths Dept. Whole Numbers National 4 NUM 1.2 Divide by 10, 100, 1000 Example : A box contains 1000 cups. How many boxes are needed to hold 7000 ? 7000 ÷ 1000 = 7 www.mathsrevision.com 19-Apr-17 Created by Mr. Lafferty Maths Dept.

Created by Mr. Lafferty Maths Dept. Whole Numbers National 4 NUM 1.2 Multiply & Divide by 10, 100, 1000 Now try Exercise 4 & 5 Ch1 (page 11) www.mathsrevision.com 19-Apr-17 Created by Mr. Lafferty Maths Dept.

Created by Mr. Lafferty Maths Dept. Starter Questions National 4 NUM 1.2 www.mathsrevision.com 36o 19-Apr-17 Created by Mr. Lafferty Maths Dept.

Created by Mr. Lafferty Maths Dept. Whole Numbers National 4 NUM 1.2 Multiply or Divide by 20,300,4000 Learning Intention Success Criteria 1. Understand the two step process to multiply or divide by 20, 300 etc… 1. To explain how to divide by 20, 300, 4000 etc using our knowledge so far. www.mathsrevision.com 2. Show all working. 19-Apr-17 Created by Mr. Lafferty Maths Dept.

Whole Numbers www.mathsrevision.com National 4 NUM 1.2 Multiply or Divide by 20,300,4000 By combining our knowledge so far of “multiplying / dividing by 10, 100, 1000” and “multiplying / dividing by a single digit” we can do harder calculations. We use a TWO step process. www.mathsrevision.com Example 1 : Calculate 20 x 52 20 can be written as 2 x 10 so we have : 2 x 10 x 52 = Step 1 : 10 x 52 = 520 Step 2 : 2 x 520 = 1040 19-Apr-17 Created by Mr. Lafferty Maths Dept.

Created by Mr. Lafferty Maths Dept. Whole Numbers National 4 NUM 1.2 Multiply or Divide by 20,300,4000 Example 2 : Calculate 44 x 30 30 can be written as 10 x 3 so we have : 44 x 10 x 3 = Step 1 : 44 x 10 = 440 Step 2 : 440 x 3 = 1320 www.mathsrevision.com Example 3 : Calculate 300 x 35 300 can be written as 3 x 100 so we have : 3 x 100 x 35 = Step 1 : 100 x35 = 3500 Step 2 : 3500 x 3 = 10500 19-Apr-17 Created by Mr. Lafferty Maths Dept.

Created by Mr. Lafferty Maths Dept. Whole Numbers National 4 NUM 1.2 Multiply or Divide by 20,300,4000 Example 4 : Calculate 16000 ÷ 200 Since 200 divide by 100 then divide by 2: 16000 ÷ 100 ÷ 2 = www.mathsrevision.com 160 Step 1 : 16000 ÷ 100 = 80 Step 2 : 160 ÷ 2 = 19-Apr-17 Created by Mr. Lafferty Maths Dept.

Created by Mr. Lafferty Maths Dept. Whole Numbers National 4 NUM 1.2 Multiply or Divide by 20,300,4000 Example 5 : Calculate 120000 ÷ 6000 Since 6000 divide by 1000 then divide by 6: 120000 ÷ 1000 ÷ 6 = www.mathsrevision.com 120 Step 1 : 120000 ÷ 1000 = 20 Step 2 : 120 ÷ 6 = 19-Apr-17 Created by Mr. Lafferty Maths Dept.

Created by Mr. Lafferty Maths Dept. Whole Numbers National 4 NUM 1.2 Multiply or Divide by 20,300,4000 Now try Ex 6 & 7 Ch1 (page 12) www.mathsrevision.com 19-Apr-17 Created by Mr. Lafferty Maths Dept.