ROUNDING FRACTIONS & MIXED NUMBERS- ESTIMATING SUMS AND DIFFERENCES. confidential

REVIEW Write each fraction in simplest form a) 3 = 1 18 6 b) 21 = ¾ 28 18 6 b) 21 = ¾ 28 c) 6 = 3 38 19 confidential

Review Write each improper fractions as a mixed number 11 = 1 1 15 = 1 2 10 10 9 3 Find the LCD of 1 and 4 3 9 LCD = 9 confidential

ROUNDING FRACTIONS AND MIXED NUMBERS confidential

ROUNDING FRACTIONS AND MIXED NUMBERS To round to the nearest half, we can use certain guidelines: ROUND UP : If the numerator is almost as large as the denominator, round the number up to the next whole number. Example: 7 rounds to 1 8 7 is almost as large as 8. confidential

Rounding fractions ii) ROUND TO ½ : If the numerator is about half of the denominator, round the fraction to ½. Example : 2 3 rounds to 2 ½ 8 3 is about half of 8 confidential

ROUNDING FRACTIONS iii) ROUND DOWN : If the numerator is much smaller than the denominator, round the number down to the whole number. Example: 1/8 rounds to 0. confidential

Examples- Round to the nearest half 6 The numerator of 1 is much smaller than the denominator. So 3 1 rounds to 3. confidential

Example – 2 Round 1 5 to the nearest half. 8 The numerator 5 is about half of the denominator 8. So, 1 5 = 1 ½ confidential

Example – 3 Round 8 8 to the nearest half. 9 since the numerator of the fractional part is almost equal to the denominator. So 8 8 rounds to 9. confidential

Your Turn Round each number to the nearest half 8 1 = 8 12 2 9 = 3 10 8 1 = 8 12 2 9 = 3 10 5 = ½ confidential

Use rounding to solve a problem If you need 1 ¼ kilograms of flour needed to make sweets, should you buy 1 ½ kilograms or 1 kilogram? Answer : Since 1 kilogram is less than 1¼ kilograms, we should round up and buy 1 ½ kilograms. confidential

BREAK confidential

ESTIMATING SUMS AND DFFERENCES confidential

REVIEW Estimate using rounding: a) 2.3 + 7.9 + 4.1 = 2 + 8 + 4 = 14 b) 9.3 – 4.758 = 9 – 5 = 4 c) 12.006 + 5. 21 – 4.23 = 12 + 5 – 4 = 13 confidential

Estimating Sums and Differences We can estimate sums and differences of fractions by rounding each fraction to the nearest half. Then add or subtract. confidential

Estimate Sums ☼ Estimate 5 + 11 8 12 5 + 11 = ½ + 1 = 1 ½ 8 12 8 12 5 rounds to ½ 8 11 Rounds to 1 12 5 + 11 = ½ + 1 = 1 ½ 8 12 confidential

Estimate Differences Estimate 7 - 1 13 6 7 Rounds to ½ 13 13 6 7 Rounds to ½ 13 1 Rounds to 0 6 7 - 1 = ½ - 0 = ½ 13 6 confidential

Your Turn Estimate: 1. 2 + 7 = ½ +1 = 1 ½ 5 8 2. 6 + 4 = ½ + ½ = 1 1. 2 + 7 = ½ +1 = 1 ½ 5 8 2. 6 + 4 = ½ + ½ = 1 13 9 3. 9 - 4 = 1 – ½ = ½ 10 9 4. 6 - 3 = ½ - ½ = 0 9 7 confidential

Mixed Number Sum And Differences We can estimate sums and differences of mixed numbers by rounding each number to the nearest whole number. confidential

Example – Mixed Number Sum Estimate 4 5 + 2 1 6 5 4 5 rounds to 5. 2 1 rounds to 2 6 5 Estimate 5 – 2 = 7 confidential

Example – Mixed Difference Estimate 2 5 - 2 8 5 2 5 - 2 = 2 ½ - ½ = 2 8 5 confidential

Your turn Estimate 3 1 + 1 5 = 3 + 2 = 5 8 6 2 7 - 1 8 = 3 – 2 = 1 8 9 3 1 + 1 5 = 3 + 2 = 5 8 6 2 7 - 1 8 = 3 – 2 = 1 8 9 confidential

Let’s have fun http://www.thekidzpage.com/freekidsgames/xword/fairytalepuzzle.html confidential

Round up to solve a problem The width of a room is 9 ¼ feet and length of a room is 12 ½ feet. About how much border the room will have? Width = 10 feet Length = 13 Border is about 10 + 10 + 13 + 13 = 46 confidential

Your turn Estimate the perimeter of rectangle if length is 13 9 inches an breadth is 2 ¼ in 11 Length = 14 and Breadth = 2 Perimeter = 14 + 14 + 2+ 2 = 32 confidential

Practice Problems Round each number to the nearest half 1. 2 4/5 = 3 1. 2 4/5 = 3 2. 4 4/9 = 4 ½ 3. 6 11/12 = 7 4. 3 2/3 = 3 ½ 5. 6 1/7 = 6 confidential

Practice Problems James walked 6 5 miles. To the nearest 8 half male, how many miles did she walk. To the nearest half, he walked about 6 ½ miles. confidential

Practice Problems Estimate 9/10 – ½ = 1 – ½ = ½ 3/8 – 1/9 = ½ - 0 = ½ 9/10 – ½ = 1 – ½ = ½ 3/8 – 1/9 = ½ - 0 = ½ 1 9/10 – 1 1/8 = 2 – 1 = 1 4 1/3 + 1 1/9 = 4 + 1 = 5 6 ¼ + 2 5/6 + 3 3/8 = 6 + 3 + 3 = 12 confidential

Review To round to the nearest half: If the numerator s almost as large as the denominator, round the number to the nearest half If the numerator is about half of the denominator, round the fraction to ½. If the numerator is much smaller than the denominator, round the number down to the whole number. confidential

That's all for today confidential