30
Multiplying two-digit numbers
Textbook: Part 1, lesson 30, pp. 93–95
GoalLearn to multiply a two-digit number by a two-digit number.
New words
income · daromadexpense · xarajatpartial product · to‘liq ko‘paytmatens place · o‘nliklar xonasi
Explanation
To multiply a two-digit number by a two-digit number, multiply the first number by the ones of the second, then by its tens, and add the two products. The product by the tens is written shifted one place to the left (the last zero is usually left out). This rests on the distributive property: 32 × 12 = 32 × (10 + 2) = 320 + 64.
Worked examples
32 × 12 = 32 × 10 + 32 × 2 = 320 + 64 = 384.
24 × 25: 24 × 5 = 120; 24 × 20 = 480; 120 + 480 = 600.
Class activity
“Two steps”: pairs multiply in a column. One child finds the product by the ones, the other the product by the tens, then they add.
Practice
1
45 × 12 = ?
540
2
91 × 86 = ?
7826
3
59 × 68 = ?
4012
4
A family pays 38 thousand so‘m for the internet each month. How many thousand so‘m do they pay in a year?
456
5
A room is 18 m long and 14 m wide. What is its area in m²?
252
6
Father earns 6 800 000, mother 4 200 000 and grandmother’s pension is 950 000 so‘m. What is the family’s monthly income?
11950000