Warm Up Problem Four potted plants cost $88. What is the price per plant?

Estimate Products of Fractions Lesson 4-1

Objectives I can estimate the product of fractions. I can define compatible numbers and explain how they are useful for estimating.

To multiply fractions or find a fraction of a #: Step 1: Divide by the denominator. Step 2: Multiply by the numerator.

Example 1 Estimate 1 4 x 13. Method 1: Use a Model 1. Divide the bar into 4 sections (total is 12) 2. Each section is 1 4 of 12, or 3. Method 2: Use compatible numbers. 13 ≈ 12 12 ÷ 4 = 3 So 1 4 x 13 is about 3. -----------------------------------------------12------------------------------------------------ 3

Example 2 Estimate 2 5 of 11. Step 1: 11 ≈ 10 Step 2: Divide by the denominator: 10 ÷ 5 = 2 Step 3: Multiply by the numerator: 2 x 2 = 4 So, 2 5 of 11 is about 4. ------------------------------------------------10-------------------------------------------------- 2

Got It? Estimate the products for the following problems: 1) 1 5 x 16 2) 5 6 of 13 3) 3 4 of 23

Estimate by Rounding to 1, 0, or 1 2 If the numerator of a fraction is almost as big as the denominator, round up to 1. 𝟕 𝟖 rounds to 1 If the numerator is much smaller than the denominator, round down 0. 𝟏 𝟖 rounds to 0 If the numerator is close to half of the fraction, round to 𝟏 𝟐

Example 3 Estimate 1 3 x 7 9 . 1 3 ≈ 1 2 7 9 ≈ 1 1 2 x 1 = 1 2 So, 1 3 x 7 9 is about 1 2 .

Example 4 Estimate 1 9 x 4 5 . 1 9 ≈ 0 4 5 ≈ 1 0 x 1 = 0 1 9 ≈ 0 4 5 ≈ 1 0 x 1 = 0 So, 1 9 x 4 5 is about 0.

Got It? 3) 5 8 x 9 10 4) 5 6 x 9 10 5) 5 6 x 1 9

Example 5 Estimate the area of the flowerbed. Round each mixed number to the nearest whole number. 14 7 8 ft ≈15 ft 6 1 8 ft ≈ 6 ft 6 x 15 = 90 So the area is about 90 𝑓𝑡 2 .

Got It? A kitchen measures 26 1 6 feet by 9 2 3 feet. Estimate the area of the kitchen.

Homework Hints #10. (The fraction of NOT rain) x 90