3
Review: operations with multi-digit numbers (practice)
Textbook: Part 1, lesson 3, pp. 10–12
GoalReview multiplying and dividing multi-digit numbers and the properties of multiplication.
New words
product · ko‘paytmaquotient · bo‘linmalong division · burchakli bo‘lishequation · tenglama
Explanation
The commutative and associative properties work for multiplication too: 25 × 11 × 4 = (25 × 4) × 11 = 1 100. To multiply by a multi-digit number we multiply by each place separately and add the results. We divide with long division and check by multiplying.
Worked examples
346 × 27 = 346 × 20 + 346 × 7 = 6 920 + 2 422 = 9 342.
18 360 : 24 = 765. Check: 24 × 765 = 18 360.
Class activity
“Check partners”: one child solves a multiplication, the partner checks it by dividing; then they swap roles.
Practice
1
Calculate conveniently: 25 × 13 × 4.
1300
2
Work out 408 × 36.
14688
3
Work out 27 540 : 45.
612
4
Solve x : 25 = 48. What is x?
1200