Multiplication Using the Lattice Method including multiplication of

Multiplication Using the Lattice Method including multiplication of decimals

What’s It All About? You are going to learn: How to multiply two whole numbers. What skills should you have already? You need to be able to multiply up to 9 × 9 and add single digit numbers.

Multiplication Using Lattice Demo Calculate 572 × 14 Draw a box. You need three squares across and two squares down. Because 5 7 2 has three digits and 1 4 has two digits …

Multiplication Using Lattice Demo Cut each square diagonally in half. Write the numbers to be multiplied around the top and right edges. 5 7 2 1 4 Use a highlighter pen to highlight every other diagonal stripe.

Multiplication Using Lattice Demo Multiply the digits at the top and right of each cell and write the answer in the cell. 5 Ten Thousands 7 0 2 0 5 2 0 7 2 0 8 8 Hundreds Tens Units The digits in each diagonal stripe all have the same place value. . . 1 4

Multiplication Using Lattice Demo Add up each stripe. Write the total for each stripe at the end of the stripe. 5 Ten Thousands 0 7 0 5 2 0 7 2 0 2 2 0 8 8 Hundreds Tens Units Now we add up the digits, starting with the units corner. . . 1 4

Multiplication Using Lattice Demo Add up each stripe. Write the total for each stripe at the end of the stripe. 5 0 7 0 0 5 8 21 0 0 Always write down your answer. . . 2 1 0 7 2 2 0 8 8 572 × 14 = 8008 1 4

Question 1 (with answer) Calculate 76 × 21 7 1 1 1 5 0 6 2 4 0 7 9 6 6 2 1 76 × 21 = 1596

Question 2 (with answer) Work out 152 × 34 1 0 5 5 0 0 1 3 1 6 5 0 2 4 2 8 0 6 3 4 8 152 × 34 = 5168

Question 3 (with answer) Calculate 237 × 14 2 0 3 3 0 0 1 18 3 0 0 2 7 7 3 2 1 8 2 1 1 4 8 237 × 14 = 3318

Your Turn 1 532 × 65 2 63 × 51 3 234 × 97 4 7165 × 4 5 37 × 45 6 103 × 54

Decimal Multiplication (one decimal number) Calculate 3. 5 × 31 First step is identical to whole numbers. Second step – draw a line through the decimal point. 3 5 1 0 **Put the decimal 1 1 3 5 9 number at the top** 0 0 0 3 5 1 8 5 Decimal point goes at the end of the line 3. 5 × 31 = 108. 5

Decimal Multiplication (one decimal number) Calculate 3. 5 × 31 First step is identical to whole numbers. Second step – draw a line through the decimal point. 3 5 Decimal point goes 1 0 at the end of the line. 1 1 9 3 5 0 0 0 5 3 8 5 1 Explain why this works. 35 × 31 = 1085 and so 3. 5 × 31 = 108. 5

Decimal Multiplication (two decimal numbers) Work out 15. 6 × 7. 4 If the lines meet in the middle of the box then go down the slide. 1 1 1 0 1 5 2 2 4 5 6 4 3 7 0 4 4 7 4 4 15. 6 × 7. 4 = 115. 44

Decimal Multiplication (two decimal numbers) Work out 15. 6 × 7. 4 If the lines meet in the middle of the box then go down the slide. 1 1 1 0 1 7 6 4 3 2 5 2 2 4 5 Explain why this works. 5 4 0 4 4 7 4 156 × 74 = 11544 and so 15. 6 × 7. 4 = 115. 44

Question 4 (with answer) Calculate 9. 37 × 1. 2 9 1 1 0 1 11 9 7 0 0 18 2 3 7 3 1 0 4 6 4 1 2 4 9. 37 × 1. 2 = 11. 244

Question 5 (with answer) Calculate 61 × 9. 8 9 5 4 5 9 10 8 8 4 0 8 9 7 6 1 Remember – put the decimal at the top 8 61 × 9. 8 = 597. 8

Question 6 (with answer) Calculate 7. 5 × 0. 3 7 0 0 0 2 2 5 0 0 1 1 2 5 0 3 5 7. 5 × 0. 3 = 2. 25

Your Turn 1 53. 4 × 65 2 6. 3 × 6. 1 3 2. 34 × 45 4 1. 65 × 4 5 3. 8 × 4. 2 6 1. 03 × 5. 6

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