7
Review: the distributive property
Textbook: Part 1, lesson 7, pp. 22–24
GoalReview the distributive property of multiplication and use it in calculations.
New words
distributive property · taqsimot xossasibracket · qavssum · yig‘indidifference · ayirma
Explanation
To multiply a sum by a number, multiply each addend by that number and add the results: (a + b) × c = a × c + b × c. The same works for a difference: (a − b) × c = a × c − b × c. This helps us multiply bigger numbers in our heads.
Worked examples
(20 + 7) × 5 = 20 × 5 + 7 × 5 = 100 + 35 = 135.
8 × 63 = 8 × 60 + 8 × 3 = 480 + 24 = 504.
Class activity
“Split and multiply”: in pairs, children solve 6 × 47 as 6 × 40 and 6 × 7, then continue with other numbers. The fastest correct pair wins.
Practice
1
(30 + 4) × 6 = ?
204
2
Calculate 7 × 49 as 7 × 50 − 7 × 1.
343
3
Calculate in a convenient way: 73 × 8 + 27 × 8.
800
4
An orchard has 6 rows of apple trees with 20 trees each, and 6 more rows with 5 trees each. How many trees are there in total?
150