 # Multiplication Using the Lattice Method including multiplication of decimals.

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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 …

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

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

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

Add up each stripe. Write the total for each stripe at the end of the stripe. 5 7 2 Multiplication Using Lattice Demo 1 4 0 5 0 7 0 2 0 2 8 0 8 08 0 8 0 1 1 Always write down your answer... 572 × 14 = 8008

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

Question 2 (with answer) Work out 152 × 34 1 5 2 3434 0 3 1 5 0 6 0 4 2 0 8 0 5 68 1 1 152 × 34 = 5168

Question 3 (with answer) Calculate 237 × 14 2 3 7 1414 0 2 0 3 0 7 0 8 1 2 8 0 3 18 3 1 237 × 14 = 3318 1

Your Turn 1532 × 65 263 × 51 3234 × 97 4 7165 × 4 537 × 45 6103 × 54

Calculate 3.5 × 31 First step is identical to whole numbers. Second step – draw a line through the decimal point. 1 5 Decimal Multiplication (one decimal number) 3 5 3 1 1 0 8 3.5 × 31 = 108.5 0 9 0 3 0 5 5 1 Decimal point goes at the end of the line **Put the decimal number at the top**

Calculate 3.5 × 31 First step is identical to whole numbers. Second step – draw a line through the decimal point. 1 5 Decimal Multiplication (one decimal number) 3 5 3 1 1 0 8 35 × 31 = 1085 and so 3.5 × 31 = 108.5 0 9 0 3 0 5 5 1 Decimal point goes at the end of the line. Explain why this works.

Decimal Multiplication (two decimal numbers) Work out 15.6 × 7.4 1 5 6 7474 0 7 3 5 4 2 0 4 2 0 2 4 1 1 4 4 5 1 15.6 × 7.4 = 115.44 If the lines meet in the middle of the box then go down the slide. 1

Decimal Multiplication (two decimal numbers) Work out 15.6 × 7.4 1 5 6 7474 0 7 3 5 4 2 0 4 2 0 2 4 1 1 44 5 1 156 × 74 = 11544 and so 15.6 × 7.4 = 115.44 If the lines meet in the middle of the box then go down the slide. Explain why this works. 1

Question 4 (with answer) Calculate 9.37 × 1.2 9 3 7 1212 0 9 0 3 0 7 1 8 0 6 1 4 1 1 44 2 1 9.37 × 1.2 = 11.244 1 1

Question 5 (with answer) Calculate 61 × 9.8 9 8 6 1 5 9 7 61 × 9.8 = 597.8 5 4 8 0 9 0 8 8 1 Remember – put the decimal at the top

Question 6 (with answer) Calculate 7.5 × 0.3 7 5 0 3 0 2 2 7.5 × 0.3 = 2.25 0 2 1 5 5

153.4 × 65 26.3 × 6.1 32.34 × 45 41.65 × 4 53.8 × 4.2 61.03 × 5.6 Your Turn

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